Encoder & Knob dimensions clarification

[hoijui]

I would like to clarify some things for me, and would offer to then adjust the build-guide accordingly, if you wish so.

You suggest a short EC11 encoder. The one you give as an example has a shaft-height of 15mm.
20mm and 15mm seem to be the most common heights, but there are also 12.5mm and 9.5mm. I imagine those would be pore problematic, to find a good know for, and I don;t know if it makes sense to choose them that short anyway.. could it make sense, or would it maybe be good to recommend 15mm height directly?
The knob you designed, if I saw that right, has a height of 15mm and a diameter of 22mm. Does that mean, the encoders shaft-height and the knob height should be equal?
I would also add that the 22mm you suggest are the diameter.
Is 22mm also the maximum diameter to not block the keys or fingers while one is not using the knob?