diff --git a/plugins/image-prioritizer/helper.php b/plugins/image-prioritizer/helper.php
index e80b8f41c..9b1c72c15 100644
--- a/plugins/image-prioritizer/helper.php
+++ b/plugins/image-prioritizer/helper.php
@@ -270,33 +270,30 @@ static function ( $host ) {
  * @since n.e.x.t
  * @access private
  *
- * @param bool|WP_Error|mixed  $validity   Validity. Valid if true or a WP_Error without any errors, or invalid otherwise.
- * @param OD_Strict_URL_Metric $url_metric URL Metric, already validated against the JSON Schema.
- * @return bool|WP_Error Validity. Valid if true or a WP_Error without any errors, or invalid otherwise.
+ * @param array<string, mixed>|mixed $data URL Metric data.
+ * @return array<string, mixed> Sanitized URL Metric data.
  *
  * @noinspection PhpDocMissingThrowsInspection
- * @throws OD_Data_Validation_Exception Except it won't because lcpElementExternalBackgroundImage is not a required property.
  */
-function image_prioritizer_filter_store_url_metric_validity( $validity, OD_Strict_URL_Metric $url_metric ) {
-	if ( ! is_bool( $validity ) && ! ( $validity instanceof WP_Error ) ) {
-		$validity = (bool) $validity;
+function image_prioritizer_filter_url_metric_data_pre_storage( $data ): array {
+	if ( ! is_array( $data ) ) {
+		$data = array();
 	}
 
-	$data = $url_metric->get( 'lcpElementExternalBackgroundImage' );
-	if ( is_array( $data ) && isset( $data['url'] ) && is_string( $data['url'] ) ) { // Note: The isset() and is_string() checks aren't necessary since the JSON Schema enforces them to be set.
-		$image_validity = image_prioritizer_validate_background_image_url( $data['url'] );
+	if ( isset( $data['lcpElementExternalBackgroundImage']['url'] ) && is_string( $data['lcpElementExternalBackgroundImage']['url'] ) ) {
+		$image_validity = image_prioritizer_validate_background_image_url( $data['lcpElementExternalBackgroundImage']['url'] );
 		if ( is_wp_error( $image_validity ) ) {
 			/**
 			 * No WP_Exception is thrown by wp_trigger_error() since E_USER_ERROR is not passed as the error level.
 			 *
 			 * @noinspection PhpUnhandledExceptionInspection
 			 */
-			wp_trigger_error( __FUNCTION__, $image_validity->get_error_message() . ' Background image URL: ' . $data['url'] );
-			$url_metric->unset( 'lcpElementExternalBackgroundImage' );
+			wp_trigger_error( __FUNCTION__, $image_validity->get_error_message() . ' Background image URL: ' . $data['lcpElementExternalBackgroundImage']['url'] );
+			unset( $data['lcpElementExternalBackgroundImage'] );
 		}
 	}
 
-	return $validity;
+	return $data;
 }
 
 /**
diff --git a/plugins/image-prioritizer/hooks.php b/plugins/image-prioritizer/hooks.php
index fbfe8c6b3..63420cd6d 100644
--- a/plugins/image-prioritizer/hooks.php
+++ b/plugins/image-prioritizer/hooks.php
@@ -13,4 +13,4 @@
 add_action( 'od_init', 'image_prioritizer_init' );
 add_filter( 'od_extension_module_urls', 'image_prioritizer_filter_extension_module_urls' );
 add_filter( 'od_url_metric_schema_root_additional_properties', 'image_prioritizer_add_element_item_schema_properties' );
-add_filter( 'od_url_metric_storage_validity', 'image_prioritizer_filter_store_url_metric_validity', 10, 2 );
+add_filter( 'od_url_metric_data_pre_storage', 'image_prioritizer_filter_url_metric_data_pre_storage' );
diff --git a/plugins/image-prioritizer/tests/test-helper.php b/plugins/image-prioritizer/tests/test-helper.php
index 45e91cccd..05de49635 100644
--- a/plugins/image-prioritizer/tests/test-helper.php
+++ b/plugins/image-prioritizer/tests/test-helper.php
@@ -747,78 +747,34 @@ public function test_image_prioritizer_validate_background_image_url( Closure $s
 	 *
 	 * @return array<string, mixed>
 	 */
-	public function data_provider_to_test_image_prioritizer_filter_store_url_metric_validity(): array {
+	public function data_provider_to_test_image_prioritizer_filter_url_metric_data_pre_storage(): array {
 		return array(
-			'pass_through_true'          => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( true, $url_metric );
-				},
-				'assert' => function ( $value ): void {
-					$this->assertTrue( $value );
-				},
-			),
-
-			'pass_through_false'         => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( false, $url_metric );
-				},
-				'assert' => function ( $value ): void {
-					$this->assertFalse( $value );
-				},
-			),
-
-			'pass_through_truthy_string' => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( 'so true', $url_metric );
-				},
-				'assert' => function ( $value ): void {
-					$this->assertTrue( $value );
-				},
-			),
-
-			'pass_through_falsy_string'  => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( '', $url_metric );
-				},
-				'assert' => function ( $value ): void {
-					$this->assertFalse( $value );
-				},
-			),
-
-			'pass_through_wp_error'      => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( new WP_Error( 'bad', 'Evil' ), $url_metric );
-				},
-				'assert' => function ( $value ): void {
-					$this->assertInstanceOf( WP_Error::class, $value );
-					$this->assertSame( 'bad', $value->get_error_code() );
-				},
-			),
-
-			'invalid_external_bg_image'  => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
-					$sample_url_metric_data['lcpElementExternalBackgroundImage'] = array(
+			'invalid_external_bg_image' => array(
+				'set_up' => static function ( array $url_metric_data ): array {
+					$url_metric_data['lcpElementExternalBackgroundImage'] = array(
 						'url'   => 'https://bad-origin.example.com/image.jpg',
 						'tag'   => 'DIV',
 						'id'    => null,
 						'class' => null,
 					);
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( true, $url_metric );
+					$url_metric_data['viewport']['width']  = 10101;
+					$url_metric_data['viewport']['height'] = 20202;
+					return $url_metric_data;
 				},
-				'assert' => function ( $value, OD_Strict_URL_Metric $url_metric ): void {
-					$this->assertTrue( $value );
-					$this->assertNull( $url_metric->get( 'lcpElementExternalBackgroundImage' ) );
+				'assert' => function ( array $url_metric_data ): void {
+					$this->assertArrayNotHasKey( 'lcpElementExternalBackgroundImage', $url_metric_data );
+					$this->assertSame(
+						array(
+							'width'  => 10101,
+							'height' => 20202,
+						),
+						$url_metric_data['viewport']
+					);
 				},
 			),
 
-			'valid_external_bg_image'    => array(
-				'set_up' => static function ( array $sample_url_metric_data ): array {
+			'valid_external_bg_image'   => array(
+				'set_up' => static function ( array $url_metric_data ): array {
 					$image_url = home_url( '/good.jpg' );
 
 					add_filter(
@@ -843,18 +799,20 @@ static function ( $pre, $parsed_args, $url ) use ( $image_url ) {
 						3
 					);
 
-					$sample_url_metric_data['lcpElementExternalBackgroundImage'] = array(
+					$url_metric_data['lcpElementExternalBackgroundImage'] = array(
 						'url'   => $image_url,
 						'tag'   => 'DIV',
 						'id'    => null,
 						'class' => null,
 					);
-					$url_metric = new OD_Strict_URL_Metric( $sample_url_metric_data );
-					return array( true, $url_metric );
+
+					$url_metric_data['viewport']['width']  = 30303;
+					$url_metric_data['viewport']['height'] = 40404;
+					return $url_metric_data;
 				},
-				'assert' => function ( $value, OD_Strict_URL_Metric $url_metric ): void {
-					$this->assertTrue( $value );
-					$this->assertIsArray( $url_metric->get( 'lcpElementExternalBackgroundImage' ) );
+				'assert' => function ( array $url_metric_data ): void {
+					$this->assertArrayHasKey( 'lcpElementExternalBackgroundImage', $url_metric_data );
+					$this->assertIsArray( $url_metric_data['lcpElementExternalBackgroundImage'] );
 					$this->assertSame(
 						array(
 							'url'   => home_url( '/good.jpg' ),
@@ -862,7 +820,14 @@ static function ( $pre, $parsed_args, $url ) use ( $image_url ) {
 							'id'    => null,
 							'class' => null,
 						),
-						$url_metric->get( 'lcpElementExternalBackgroundImage' )
+						$url_metric_data['lcpElementExternalBackgroundImage']
+					);
+					$this->assertSame(
+						array(
+							'width'  => 30303,
+							'height' => 40404,
+						),
+						$url_metric_data['viewport']
 					);
 				},
 			),
@@ -870,19 +835,18 @@ static function ( $pre, $parsed_args, $url ) use ( $image_url ) {
 	}
 
 	/**
-	 * Tests image_prioritizer_filter_store_url_metric_validity().
+	 * Tests image_prioritizer_filter_url_metric_data_pre_storage().
 	 *
-	 * @dataProvider data_provider_to_test_image_prioritizer_filter_store_url_metric_validity
+	 * @dataProvider data_provider_to_test_image_prioritizer_filter_url_metric_data_pre_storage
 	 *
-	 * @covers ::image_prioritizer_filter_store_url_metric_validity
+	 * @covers ::image_prioritizer_filter_url_metric_data_pre_storage
 	 * @covers ::image_prioritizer_validate_background_image_url
 	 */
-	public function test_image_prioritizer_filter_store_url_metric_validity( Closure $set_up, Closure $assert ): void {
-		$sample_url_metric_data        = $this->get_sample_url_metric( array() )->jsonSerialize();
-		list( $validity, $url_metric ) = $set_up( $sample_url_metric_data );
+	public function test_image_prioritizer_filter_url_metric_data_pre_storage( Closure $set_up, Closure $assert ): void {
+		$url_metric_data = $set_up( $this->get_sample_url_metric( array() )->jsonSerialize() );
 
-		$validity = image_prioritizer_filter_store_url_metric_validity( $validity, $url_metric );
-		$assert( $validity, $url_metric );
+		$url_metric_data = image_prioritizer_filter_url_metric_data_pre_storage( $url_metric_data );
+		$assert( $url_metric_data );
 	}
 
 	/**
diff --git a/plugins/image-prioritizer/tests/test-hooks.php b/plugins/image-prioritizer/tests/test-hooks.php
index 3c2e02014..416523cb1 100644
--- a/plugins/image-prioritizer/tests/test-hooks.php
+++ b/plugins/image-prioritizer/tests/test-hooks.php
@@ -14,6 +14,6 @@ public function test_hooks_added(): void {
 		$this->assertEquals( 10, has_action( 'od_init', 'image_prioritizer_init' ) );
 		$this->assertEquals( 10, has_filter( 'od_extension_module_urls', 'image_prioritizer_filter_extension_module_urls' ) );
 		$this->assertEquals( 10, has_filter( 'od_url_metric_schema_root_additional_properties', 'image_prioritizer_add_element_item_schema_properties' ) );
-		$this->assertEquals( 10, has_filter( 'od_url_metric_storage_validity', 'image_prioritizer_filter_store_url_metric_validity' ) );
+		$this->assertEquals( 10, has_filter( 'od_url_metric_data_pre_storage', 'image_prioritizer_filter_url_metric_data_pre_storage' ) );
 	}
 }
diff --git a/plugins/optimization-detective/class-od-element.php b/plugins/optimization-detective/class-od-element.php
index be8400ce4..c7f243d99 100644
--- a/plugins/optimization-detective/class-od-element.php
+++ b/plugins/optimization-detective/class-od-element.php
@@ -208,53 +208,18 @@ public function offsetSet( $offset, $value ): void {
 	}
 
 	/**
-	 * Unsets a property.
+	 * Offset to unset.
 	 *
-	 * This is particularly useful in conjunction with the `od_url_metric_schema_element_item_additional_properties` filter.
-	 * This will throw an exception if the property is required by the schema.
-	 *
-	 * @since n.e.x.t
-	 *
-	 * @param string $key Property.
+	 * This is disallowed. Attempting to unset a property will throw an error.
 	 *
-	 * @throws OD_Data_Validation_Exception When attempting to unset a property required by the JSON Schema.
-	 */
-	public function unset( string $key ): void {
-		$schema = OD_URL_Metric::get_json_schema(); // TODO: This should be a non-static method once the URL Metric is instantiated.
-		if (
-			isset( $schema['properties']['elements']['items']['properties'][ $key ]['required'] )
-			&& true === $schema['properties']['elements']['items']['properties'][ $key ]['required']
-		) {
-			throw new OD_Data_Validation_Exception(
-				esc_html(
-					sprintf(
-						/* translators: %s is the property key. */
-						__( 'The %s key is required for an item of elements in a URL Metric.', 'optimization-detective' ),
-						$key
-					)
-				)
-			);
-		}
-		unset( $this->data[ $key ] ); // @phpstan-ignore assign.propertyType (Above required check ensures $key is not isLCP, isLCPCandidate, xpath, intersectionRatio, intersectionRect, boundingClientRect.)
-		$group = $this->url_metric->get_group();
-		if ( $group instanceof OD_URL_Metric_Group ) {
-			$group->clear_cache();
-		}
-	}
-
-	/**
-	 * Unsets an offset.
-	 *
-	 * This will throw an exception if the offset is required by the schema.
-	 *
-	 * @since n.e.x.t
+	 * @since 0.7.0
 	 *
 	 * @param mixed $offset Offset.
 	 *
-	 * @throws OD_Data_Validation_Exception When attempting to unset a property required by the JSON Schema.
+	 * @throws Exception When attempting to unset a property.
 	 */
 	public function offsetUnset( $offset ): void {
-		$this->unset( (string) $offset );
+		throw new Exception( 'Element data may not be unset.' );
 	}
 
 	/**
diff --git a/plugins/optimization-detective/class-od-url-metric.php b/plugins/optimization-detective/class-od-url-metric.php
index b68045e6e..f4a4e25cc 100644
--- a/plugins/optimization-detective/class-od-url-metric.php
+++ b/plugins/optimization-detective/class-od-url-metric.php
@@ -503,33 +503,6 @@ function ( array $element ): OD_Element {
 		return $this->elements;
 	}
 
-	/**
-	 * Unsets a property from the URL Metric.
-	 *
-	 * @since n.e.x.t
-	 *
-	 * @param string $key Key to unset.
-	 * @throws OD_Data_Validation_Exception If the property is required an exception will be thrown.
-	 */
-	public function unset( string $key ): void {
-		$schema = self::get_json_schema(); // TODO: Consider capturing the schema as a private member variable once the URL Metric is constructed.
-		if ( isset( $schema['properties'][ $key ]['required'] ) && true === $schema['properties'][ $key ]['required'] ) {
-			throw new OD_Data_Validation_Exception(
-				esc_html(
-					sprintf(
-						/* translators: %s is the property key. */
-						__( 'The %s key is required at the root of a URL Metric.', 'optimization-detective' ),
-						$key
-					)
-				)
-			);
-		}
-		unset( $this->data[ $key ] ); // @phpstan-ignore assign.propertyType (Above required check ensures $key is not uuid, url, timestamp, viewport, or elements.)
-		if ( $this->group instanceof OD_URL_Metric_Group ) {
-			$this->group->clear_cache();
-		}
-	}
-
 	/**
 	 * Specifies data which should be serialized to JSON.
 	 *
diff --git a/plugins/optimization-detective/storage/rest-api.php b/plugins/optimization-detective/storage/rest-api.php
index 198b57284..940928769 100644
--- a/plugins/optimization-detective/storage/rest-api.php
+++ b/plugins/optimization-detective/storage/rest-api.php
@@ -186,85 +186,64 @@ function od_handle_rest_request( WP_REST_Request $request ) {
 	OD_Storage_Lock::set_lock();
 
 	try {
-		// The "strict" URL Metric class is being used here to ensure additionalProperties of all objects are disallowed.
-		$url_metric = new OD_Strict_URL_Metric(
-			array_merge(
-				$data,
-				array(
-					// Now supply the readonly args which were omitted from the REST API params due to being `readonly`.
-					'timestamp' => microtime( true ),
-					'uuid'      => wp_generate_uuid4(),
-					'etag'      => $request->get_param( 'current_etag' ),
-				)
+		$data = array_merge(
+			$data,
+			array(
+				// Now supply the readonly args which were omitted from the REST API params due to being `readonly`.
+				'timestamp' => microtime( true ),
+				'uuid'      => wp_generate_uuid4(),
+				'etag'      => $request->get_param( 'current_etag' ),
 			)
 		);
-	} catch ( OD_Data_Validation_Exception $e ) {
-		return new WP_Error(
-			'rest_invalid_param',
-			sprintf(
-				/* translators: %s is exception name */
-				__( 'Failed to validate URL Metric: %s', 'optimization-detective' ),
-				$e->getMessage()
-			),
-			array( 'status' => 400 )
-		);
-	}
 
-	try {
 		/**
-		 * Filters whether a URL Metric is valid for storage.
+		 * Filters the URL Metric data prior to validation for storage.
 		 *
-		 * This allows for custom validation constraints to be applied beyond what can be expressed in JSON Schema. This is
-		 * also necessary because the 'validate_callback' key in a JSON Schema is not respected when gathering the REST API
-		 * endpoint args via the {@see rest_get_endpoint_args_for_schema()} function. Besides this, the REST API doesn't
-		 * support 'validate_callback' for any nested arguments in any case, meaning that custom constraints would be able
-		 * to be applied to multidimensional objects, such as the items inside 'elements'.
+		 * This allows for custom sanitization and validation constraints to be applied beyond what can be expressed in
+		 * JSON Schema. This is also necessary because the 'validate_callback' key in a JSON Schema is not respected when
+		 * gathering the REST API endpoint args via the {@see rest_get_endpoint_args_for_schema()} function. Besides this,
+		 * the REST API doesn't support 'validate_callback' for any nested arguments in any case, meaning that custom
+		 * constraints would be able to be applied to multidimensional objects, such as the items inside 'elements'.
 		 *
 		 * This filter only applies when storing a URL Metric via the REST API. It does not run when a stored URL Metric is
-		 * loaded from the od_url_metrics post type. This means that validation logic enforced via this filter can be more
-		 * expensive, such as doing filesystem checks or HTTP requests.
+		 * loaded from the od_url_metrics post type. This means that sanitization and validation logic enforced via this
+		 * filter can be more expensive, such as doing filesystem checks or HTTP requests.
 		 *
-		 * In addition to having the filter return `false` or a non-empty `WP_Error` to block storing the URL Metric, a
-		 * plugin may also mutate the OD_URL_Metric instance passed by reference to the filter callback. This is useful
-		 * for plugins in particular to unset extended properties which couldn't be validated using JSON Schema alone.
+		 * To fail validation for the provided URL Metric data, an OD_Data_Validation_Exception exception should be thrown.
+		 * Otherwise, any filter callbacks must return an array consisting of the sanitized URL Metric data.
 		 *
 		 * @since n.e.x.t
 		 *
-		 * @param bool|WP_Error        $validity        Validity. Invalid if false or a WP_Error with errors.
-		 * @param OD_Strict_URL_Metric $url_metric      URL Metric, already validated against the JSON Schema.
-		 * @param array<string, mixed> $url_metric_data Original URL Metric data before any mutations.
+		 * @param array<string, mixed> $data URL Metric data. This is the Data type from OD_URL_Metric.
 		 */
-		$validity = apply_filters( 'od_url_metric_storage_validity', true, $url_metric, $url_metric->jsonSerialize() );
+		$data = apply_filters( 'od_url_metric_data_pre_storage', $data );
+
+		// The "strict" URL Metric class is being used here to ensure additionalProperties of all objects are disallowed.
+		$url_metric = new OD_Strict_URL_Metric( $data );
 	} catch ( Exception $e ) {
-		$error_data = array(
-			'status' => 500,
-		);
-		if ( WP_DEBUG ) {
-			$error_data['exception'] = array(
-				'class'   => get_class( $e ),
-				'message' => $e->getMessage(),
-				'code'    => $e->getCode(),
+		$error_data = array();
+		if ( $e instanceof OD_Data_Validation_Exception ) {
+			$error_message = sprintf(
+				/* translators: %s is exception name */
+				__( 'Failed to validate URL Metric: %s', 'optimization-detective' ),
+				$e->getMessage()
 			);
+			$error_data['status'] = 400;
+		} else {
+			$error_message = sprintf(
+				/* translators: %s is exception name */
+				__( 'Failed to validate URL Metric: %s', 'optimization-detective' ),
+				__( 'An unrecognized exception was thrown', 'optimization-detective' )
+			);
+			$error_data['status'] = 500;
+			if ( WP_DEBUG ) {
+				$error_data['exception_class']   = get_class( $e );
+				$error_data['exception_message'] = $e->getMessage();
+				$error_data['exception_code']    = $e->getCode();
+			}
 		}
-		$validity = new WP_Error(
-			'exception',
-			sprintf(
-				/* translators: %s is the filter name 'od_url_metric_storage_validity' */
-				__( 'An %s filter callback threw an exception.', 'optimization-detective' ),
-				'od_url_metric_storage_validity'
-			),
-			$error_data
-		);
-	}
-	if ( false === (bool) $validity || ( $validity instanceof WP_Error && $validity->has_errors() ) ) {
-		if ( false === $validity ) {
-			$validity = new WP_Error( 'invalid_url_metric', __( 'Validity of URL Metric was rejected by filter.', 'optimization-detective' ) );
-		}
-		$error_code = $validity->get_error_code();
-		if ( ! isset( $validity->error_data[ $error_code ]['status'] ) ) {
-			$validity->error_data[ $error_code ]['status'] = 400;
-		}
-		return $validity;
+
+		return new WP_Error( 'rest_invalid_param', $error_message, $error_data );
 	}
 
 	// TODO: This should be changed from store_url_metric($slug, $url_metric) instead be update_post( $slug, $group_collection ). As it stands, store_url_metric() is duplicating logic here.
@@ -277,8 +256,8 @@ function od_handle_rest_request( WP_REST_Request $request ) {
 			'status' => 500,
 		);
 		if ( WP_DEBUG ) {
-			$error_data['code']    = $result->get_error_code();
-			$error_data['message'] = $result->get_error_message();
+			$error_data['error_code']    = $result->get_error_code();
+			$error_data['error_message'] = $result->get_error_message();
 		}
 		return new WP_Error(
 			'unable_to_store_url_metric',
diff --git a/plugins/optimization-detective/tests/storage/test-rest-api.php b/plugins/optimization-detective/tests/storage/test-rest-api.php
index 0caf8b5a3..01684eb3a 100644
--- a/plugins/optimization-detective/tests/storage/test-rest-api.php
+++ b/plugins/optimization-detective/tests/storage/test-rest-api.php
@@ -41,14 +41,14 @@ static function ( array $properties ) use ( $property_name ): array {
 		};
 
 		return array(
-			'not_extended'                                => array(
+			'not_extended'                     => array(
 				'set_up'          => function (): array {
 					return $this->get_valid_params();
 				},
 				'expect_stored'   => true,
 				'expected_status' => 200,
 			),
-			'extended'                                    => array(
+			'extended'                         => array(
 				'set_up'          => function () use ( $add_root_extra_property ): array {
 					$add_root_extra_property( 'extra' );
 					$params = $this->get_valid_params();
@@ -58,84 +58,39 @@ static function ( array $properties ) use ( $property_name ): array {
 				'expect_stored'   => true,
 				'expected_status' => 200,
 			),
-			'extended_but_unset'                          => array(
-				'set_up'          => function () use ( $add_root_extra_property ): array {
-					$add_root_extra_property( 'unset_prop' );
-					add_filter(
-						'od_url_metric_storage_validity',
-						static function ( $validity, OD_URL_Metric $url_metric ) {
-							$url_metric->unset( 'extra' );
-							return $validity;
-						},
-						10,
-						2
-					);
-					$params = $this->get_valid_params();
-					$params['unset_prop'] = 'bar';
-					return $params;
-				},
-				'expect_stored'   => true,
-				'expected_status' => 200,
-			),
-			'extended_and_rejected_by_returning_false'    => array(
-				'set_up'          => function () use ( $add_root_extra_property ): array {
-					$add_root_extra_property( 'extra' );
-					add_filter( 'od_url_metric_storage_validity', '__return_false' );
-
-					$params = $this->get_valid_params();
-					$params['extra'] = 'foo';
-					return $params;
-				},
-				'expect_stored'   => false,
-				'expected_status' => 400,
-			),
-			'extended_and_rejected_by_returning_wp_error' => array(
-				'set_up'          => function () use ( $add_root_extra_property ): array {
-					$add_root_extra_property( 'extra' );
-					add_filter(
-						'od_url_metric_storage_validity',
-						static function () {
-							return new WP_Error( 'rejected', 'Rejected!' );
-						}
-					);
-
-					$params = $this->get_valid_params();
-					$params['extra'] = 'foo';
-					return $params;
-				},
-				'expect_stored'   => false,
-				'expected_status' => 400,
-			),
-			'rejected_by_returning_wp_error_with_forbidden_status' => array(
+			'rejected_by_generic_exception'    => array(
 				'set_up'          => function (): array {
 					add_filter(
-						'od_url_metric_storage_validity',
-						static function () {
-							return new WP_Error( 'forbidden', 'Forbidden!', array( 'status' => 403 ) );
+						'od_url_metric_data_pre_storage',
+						static function ( $data ): array {
+							if ( count( $data ) > 0 ) {
+								throw new Exception( 'bad' );
+							}
+							return $data;
 						}
 					);
 					return $this->get_valid_params();
 				},
 				'expect_stored'   => false,
-				'expected_status' => 403,
+				'expected_status' => 500,
 			),
-			'rejected_by_exception'                       => array(
+			'rejected_by_validation_exception' => array(
 				'set_up'          => function (): array {
 					add_filter(
-						'od_url_metric_storage_validity',
-						static function ( $validity, OD_URL_Metric $url_metric ) {
-							$url_metric->unset( 'viewport' );
-							return $validity;
-						},
-						10,
-						2
+						'od_url_metric_data_pre_storage',
+						static function ( $data ): array {
+							if ( count( $data ) > 0 ) {
+								throw new OD_Data_Validation_Exception( 'bad' );
+							}
+							return $data;
+						}
 					);
 					return $this->get_valid_params();
 				},
 				'expect_stored'   => false,
-				'expected_status' => 500,
+				'expected_status' => 400,
 			),
-			'with_cache_purge_post_id'                    => array(
+			'with_cache_purge_post_id'         => array(
 				'set_up'          => function (): array {
 					$params = $this->get_valid_params();
 					$params['cache_purge_post_id'] = self::factory()->post->create();
@@ -160,22 +115,17 @@ static function ( $validity, OD_URL_Metric $url_metric ) {
 	 * @covers ::od_trigger_page_cache_invalidation
 	 */
 	public function test_rest_request_good_params( Closure $set_up, bool $expect_stored, int $expected_status ): void {
-		$filtered_url_metric_obj  = null;
 		$filtered_url_metric_data = null;
 		$filter_called            = 0;
 		add_filter(
-			'od_url_metric_storage_validity',
-			function ( $validity, $url_metric, $url_metric_data ) use ( &$filter_called, &$filtered_url_metric_obj, &$filtered_url_metric_data ) {
-				$this->assertTrue( $validity );
-				$this->assertInstanceOf( OD_URL_Metric::class, $url_metric );
+			'od_url_metric_data_pre_storage',
+			function ( $url_metric_data ) use ( &$filter_called, &$filtered_url_metric_data ) {
 				$this->assertIsArray( $url_metric_data );
-				$filtered_url_metric_obj  = $url_metric;
 				$filtered_url_metric_data = $url_metric_data;
 				$filter_called++;
-				return $validity;
+				return $url_metric_data;
 			},
-			0,
-			3
+			0
 		);
 
 		$stored_context = null;
@@ -233,7 +183,6 @@ function ( OD_URL_Metric_Store_Request_Context $context ) use ( &$stored_context
 			);
 
 			$this->assertInstanceOf( OD_URL_Metric_Store_Request_Context::class, $stored_context );
-			$this->assertSame( $stored_context->url_metric, $filtered_url_metric_obj );
 			$this->assertSame( $stored_context->url_metric->jsonSerialize(), $filtered_url_metric_data );
 
 			// Now check that od_trigger_page_cache_invalidation() cleaned caches as expected.
diff --git a/plugins/optimization-detective/tests/test-class-od-element.php b/plugins/optimization-detective/tests/test-class-od-element.php
index 1b980d421..c4650c770 100644
--- a/plugins/optimization-detective/tests/test-class-od-element.php
+++ b/plugins/optimization-detective/tests/test-class-od-element.php
@@ -24,7 +24,6 @@ class Test_OD_Element extends WP_UnitTestCase {
 	 * @covers ::offsetExists
 	 * @covers ::offsetGet
 	 * @covers ::offsetSet
-	 * @covers ::unset
 	 * @covers ::offsetUnset
 	 * @covers ::jsonSerialize
 	 */
@@ -151,48 +150,6 @@ static function ( OD_Element $element ): void {
 			$this->assertFalse( $element->get( 'isLCP' ) );
 		}
 
-		// Try unsetting a required property.
-		$functions = array(
-			static function ( OD_Element $element ): void {
-				unset( $element['isLCP'] );
-			},
-			static function ( OD_Element $element ): void {
-				$element->unset( 'isLCP' );
-			},
-			static function ( OD_Element $element ): void {
-				$element->offsetUnset( 'isLCP' );
-			},
-		);
-		foreach ( $functions as $function ) {
-			$exception = null;
-			try {
-				$function( $element );
-			} catch ( Exception $e ) {
-				$exception = $e;
-			}
-			$this->assertInstanceOf( Exception::class, $exception );
-			$this->assertArrayHasKey( 'isLCP', $element->jsonSerialize() );
-		}
-
 		$this->assertEquals( $element_data, $element->jsonSerialize() );
-
-		// Try unsetting a non-required property.
-		$functions = array(
-			static function ( OD_Element $element ): void {
-				unset( $element['customProp'] );
-			},
-			static function ( OD_Element $element ): void {
-				$element->unset( 'customProp' );
-			},
-			static function ( OD_Element $element ): void {
-				$element->offsetUnset( 'customProp' );
-			},
-		);
-		foreach ( $functions as $function ) {
-			$cloned_element = clone $element;
-			$function( $cloned_element );
-			$this->assertFalse( $cloned_element->offsetExists( 'customProp' ) );
-			$this->assertArrayNotHasKey( 'customProp', $cloned_element->jsonSerialize() );
-		}
 	}
 }
diff --git a/plugins/optimization-detective/tests/test-class-od-url-metric.php b/plugins/optimization-detective/tests/test-class-od-url-metric.php
index df2fa0144..51b23c243 100644
--- a/plugins/optimization-detective/tests/test-class-od-url-metric.php
+++ b/plugins/optimization-detective/tests/test-class-od-url-metric.php
@@ -277,7 +277,6 @@ static function ( $value ) {
 	 * @covers ::get_json_schema
 	 * @covers ::set_group
 	 * @covers ::get_group
-	 * @covers ::unset
 	 *
 	 * @dataProvider data_provider_to_test_constructor
 	 *
@@ -337,15 +336,6 @@ static function ( OD_Element $element ) {
 		$this->assertTrue( wp_is_uuid( $url_metric->get_uuid() ) );
 		$this->assertSame( $url_metric->get_uuid(), $url_metric->get( 'uuid' ) );
 
-		$exception = null;
-		try {
-			$url_metric->unset( 'elements' );
-		} catch ( OD_Data_Validation_Exception $e ) {
-			$exception = $e;
-		}
-		$this->assertInstanceOf( OD_Data_Validation_Exception::class, $exception );
-		$url_metric->unset( 'does_not_exist' );
-
 		$serialized = $url_metric->jsonSerialize();
 		if ( ! array_key_exists( 'uuid', $data ) ) {
 			$this->assertTrue( wp_is_uuid( $serialized['uuid'] ) );
@@ -407,12 +397,6 @@ static function ( array $properties ): array {
 					$this->assertArrayHasKey( 'isTouch', $extended_data );
 					$this->assertTrue( $extended_data['isTouch'] );
 					$this->assertTrue( $extended_url_metric->get( 'isTouch' ) );
-
-					$this->assertTrue( $extended_url_metric->get( 'isTouch' ) );
-					$extended_url_metric->unset( 'isTouch' );
-					$this->assertNull( $extended_url_metric->get( 'isTouch' ) );
-					$extended_data = $extended_url_metric->jsonSerialize();
-					$this->assertArrayNotHasKey( 'isTouch', $extended_data );
 				},
 			),
 
@@ -505,13 +489,6 @@ static function ( array $properties ): array {
 					$this->assertArrayHasKey( 'isColorful', $extended_data['elements'][0] );
 					$this->assertFalse( $extended_data['elements'][0]['isColorful'] );
 					$this->assertFalse( $extended_url_metric->get_elements()[0]['isColorful'] );
-
-					$element = $extended_url_metric->get_elements()[0];
-					$this->assertFalse( $element->get( 'isColorful' ) );
-					$element->unset( 'isColorful' );
-					$this->assertNull( $element->get( 'isColorful' ) );
-					$extended_data = $extended_url_metric->jsonSerialize();
-					$this->assertArrayNotHasKey( 'isColorful', $extended_data['elements'][0] );
 				},
 			),
 
@@ -577,8 +554,6 @@ static function ( array $properties ): array {
 	 * Tests construction with extended schema.
 	 *
 	 * @covers ::get_json_schema
-	 * @covers ::unset
-	 * @covers OD_Element::unset
 	 *
 	 * @dataProvider data_provider_to_test_constructor_with_extended_schema
 	 *
diff --git a/plugins/optimization-detective/tests/test-class-od-url-metrics-group-collection.php b/plugins/optimization-detective/tests/test-class-od-url-metrics-group-collection.php
index 957acd1a4..ef05fc2ab 100644
--- a/plugins/optimization-detective/tests/test-class-od-url-metrics-group-collection.php
+++ b/plugins/optimization-detective/tests/test-class-od-url-metrics-group-collection.php
@@ -204,8 +204,6 @@ public function data_provider_sample_size_and_breakpoints(): array {
 	 *
 	 * @covers ::clear_cache
 	 * @covers OD_URL_Metric_Group::clear_cache
-	 * @covers OD_URL_Metric::unset
-	 * @covers OD_Element::unset
 	 */
 	public function test_clear_cache(): void {
 		$collection      = new OD_URL_Metric_Group_Collection( array(), md5( '' ), array(), 1, DAY_IN_SECONDS );
@@ -226,58 +224,13 @@ public function test_clear_cache(): void {
 		$this->assertSame( array(), $collection_result_cache_reflection_property->getValue( $collection ) );
 
 		// Test that adding a URL metric to a collection clears the caches.
-		add_filter(
-			'od_url_metric_schema_root_additional_properties',
-			static function ( $schema ) {
-				$schema['new_prop_at_root'] = array(
-					'type' => 'string',
-				);
-				return $schema;
-			}
-		);
-		add_filter(
-			'od_url_metric_schema_element_additional_properties',
-			static function ( $schema ) {
-				$schema['new_prop_at_element'] = array(
-					'type' => 'string',
-				);
-				return $schema;
-			}
-		);
 		$collection_result_cache_reflection_property->setValue( $collection, $populated_value );
 		$group_result_cache_reflection_property->setValue( $group, $populated_value );
-		$collection->add_url_metric(
-			$this->get_sample_url_metric(
-				array(
-					'element'       => array(
-						'xpath'               => '/*[1][self::HTML]/*[2][self::BODY]/*[1][self::IMG]',
-						'new_prop_at_element' => 'hey there',
-					),
-					'extended_root' => array(
-						'new_prop_at_root' => 'hola',
-					),
-				)
-			)
-		);
+		$collection->add_url_metric( $this->get_sample_url_metric( array() ) );
 		$url_metric = $group->getIterator()->current();
 		$this->assertInstanceOf( OD_URL_Metric::class, $url_metric );
 		$this->assertSame( array(), $collection_result_cache_reflection_property->getValue( $collection ) );
 		$this->assertSame( array(), $group_result_cache_reflection_property->getValue( $group ) );
-
-		// Test that modifying a URL Metric empties the cache of the collection and the group.
-		$collection_result_cache_reflection_property->setValue( $collection, $populated_value );
-		$group_result_cache_reflection_property->setValue( $group, $populated_value );
-		$url_metric->unset( 'new_prop_at_root' );
-		$this->assertSame( array(), $collection_result_cache_reflection_property->getValue( $collection ) );
-		$this->assertSame( array(), $group_result_cache_reflection_property->getValue( $group ) );
-
-		// Test that modifying a URL Metric element empties the cache of the collection and the group.
-		$element = $url_metric->get_elements()[0];
-		$collection_result_cache_reflection_property->setValue( $collection, $populated_value );
-		$group_result_cache_reflection_property->setValue( $group, $populated_value );
-		$element->unset( 'new_prop_at_element' );
-		$this->assertSame( array(), $collection_result_cache_reflection_property->getValue( $collection ) );
-		$this->assertSame( array(), $group_result_cache_reflection_property->getValue( $group ) );
 	}
 
 	/**