Starting to design out my build, looking for critique

[Kitwn]

There's a nice guide to designing linear power suplies here http://www.skillbank.co.uk/psu/

Whilst it's true a linear supply of a given rating can deliver significantly higher current peaks than a switch-mode supply of the same rating, you should look at the relative cost of a linear design and a suitably rated switching supply or possibly two separate supplies, one for, say, two motors on X and one for the single motors on each of Y and Z.

I can't see the point of spending a lot of time and money on building an unregulated power supply which can, even briefly, deliver far more current than is required to saturate the motors. The available current in case of a fault would also be much higher.

Kit