I have a 100 ST guy who will play 40 minutes in a game. I set it at "Foul trouble only". And when I look at the PbP he will get tired but not below tired.
I think that is working as it should. Nobody is going to go 40 without getting tired, regarless whether they are at 100 or not. (Maybe in the pre shot clock era playing a four corners offense)
My problem is with the complaining players so I make that 100 (and my 99) St guys only play 31-32 minutes, at least until the CT.