Purely for training purposes, the best way to spread the minutes is as follows (assuming Game1 is harder than Game 2 - switch them if Game 2 is harder):
Game 1: Start A-Team, Subs are C-Team
Game 2: Start B-Team, Subs are A-Team
Scrimmage: Start C-Team, sub B-Team
That is what I have been doing. You may have to balance it out to where your best 2 players are not on the A-team, but one is on the a-team, and the second best on the b-team.