the way i train my big men is a 2 week rotation unless there is a really big need to increase one skill quickly. so i would train inside shot for 2 weeks and then switch to inside defense for 2 weeks and so on, constantly repeating the process.
before starting this rotation, it is usefull to get all skill at one level ;) Because training going fsat , when the similiar skills ain't much weaker then the trained one, that also the reason for the rotation(because their are mostly at the same level).
potential basically works by the higher it is the better.
for me is it is something like, the higher is the useless waste of money ;) You could even train your all stars at a pretty high level(i'm actual u21 Coach and this "boys" get pretty feast training, the skillcap for allstars is around the level of our Senior squad but this could also be an age thing)