as monkeybiz said, it's very hard and depends a lot on the situation on field.
even taking that in consideration, I was winning 70:25 in the third quarter and still my starters were playing
it also depends on the difference in skill between your starters and your backups.
but also as monkey said, with 3 games in a week it isn't a big problem to manage the minutes, the only problem is that you sometimes can't use your best, or even second best team in a game the way you wanted due to minutes played