minWeightMagnitude in example code, 18 advised instead of 14

[rantwijk]

Wiki Page: https://github.com/iotaledger/wiki/blob/master/hackathon-guide.md#make-a-transfer

iota.api.sendTransfer('SEED', 9, 18, transfer, function(e,s)

When it comes to depth and minWeightMagnitude, we advise you to use 3 as a standard value for depth, and 18 as a standard value for minWeightMagnitude.

Where is this value 18 pulled from? Nearly everywhere else minWeightMagnitude of 14 is advised for mainnet. Running with difficulty 18 instead of 14 raises the PoW time exponentially.