If you have your starers going up against a scout team of non-starters, then you are using 44 players, leaving (including PS) 19 players, and that includes 2 kickers who won't be part of this. 17 players isin't enough for a full practice. And that's if everybody is healthy (Powerball has better odds). Also it really is just the backup QB that gets badly short changed. Other non-starters are rotated in various packages.

I will agree that something more needs to be done about getting the backup QB prepared, but a separate practice ins't feasible, unless they could make a virtual practice simulation for the backup to work with.