when i was competing, about 4 seasons ago, my idea was that a player with stamina 9 needs 80-85 to be in shape.
And it worked well for main of them apart one Vasallo who needed 75-79.
It is like every player has his own reaction to minutes
For stamina 7, 70-75 is the right minutes IMO.
S52 CUP WINNER "non dire gatto se non ce l'hai nel sacco"