Yes, certain skills do train faster in shorter players. Mine were in the 6'1'' to 6'4'' range... with 1 exception.
Anyway I probably wasn't clear, but it was only the same exact players I was using to compare both training types . (I would play them out of position various weeks). For example when training "guards only" i might play my sg at pg, & sf as sg... that type of thing. So by comparing only the same players, height & age are pretty much eliminated as factors.
Hmm, that's an interesting theory. & agreed it would be kinda neat. But according to FAQ, it doesn't seem to matter...
(144856.30) (2nd paragraph)
In order for a player to receive full training in a given week you must play him 48 minutes at the position(s) you selected to train that week. For example, if you decided to train jump shot on guards (PG/SG) your player would need to amass 48 minutes at either PG, SG, or a combination of the two.