Well, you're right.
The focus of the question is about the player that I try to built. If he is injured I loose a week anyway, two in my case :'(
For my team and my season GS is of course the best option. But GS is useless for franchise guy like a "normal" skill-training.
Great your hint for stamina and FT.
But with 1 more level don't you like have better performance (for more minutes or at the line)?