What you mean with "garbage time"?
So with 9 or 10 in ST a player can play 96 Min/week and still keep shape at 8 or 9?
If your team leads by 20 or more before the last quarter, the starting 5 sit it out (if you have enough substitutes selected of course). That means your starters get ~32-36 min per game. And 72 min per week is perfectly fine to keep decent game shape even on a low-stamina player.