As for my opinion, what about letting people chose which players are trained. But these players, as a result of this extra training, would suffer a loss in performance (X%) ?
That would also get right of players forced to play 48min a game to receive 100% training.
Let me know if I understood that correctly.
So if player plays during the week and his selected for training instead of having played 30-40 min a match with 100% he'll play at lower efficiency like 75%, something like additional stamina penalty?
Or it should affect his GS, if he's on training then he needs to play less minutes to be in good Game Shape?