if you have a decent bench, you can start your bench players in games you know you'll win, giving your starters a rest. On the other hand, if you're facing a much stronger team which you're sure to lose against, start your bench players. Usually you'll have 1 of these games in your week, making it possible to start your star players once and let them come of the bench the other time. If they get less than 48 minutes as a result, you'll always have the option to play them off the bench in your scrimmage.
Of course, there will be weeks in which you'll need your starters to start both league games, but the impact will be less severe if they get less minutes the other weeks.