But, also, there is the real world

Consider power consumption
Your power supply must provide enough current
Your tracks, connectors, external cables must be big enough
Are you battery-driven?  Hmm... interesting....

Consider heath
Your components get hot and must dissipate
Your power supply gets hot and must dissipate

Consider mechanichs
Coordinate with the mechanical engineer
Try to ease maintainance, and component replacement

Consider noise and interference
Switching or linear supplies?
Beware of capacitive coupling between signals
Beware of high impedance critical signals
With high currents, consider the ground return path