There are very different philosophies that work... I think it depends mostly upon how easy the tumbling skills are in a routine. I know when our gym first had level 5, it was one or two full outs a practice. Now there's more. It comes down to risk management. This year we have a much more talented team than in the past and they don't all throw their hardest skills, for the most part, all of the tumbling is relatively easy for them, and they have been throwing all of the skills for the better part of a calendar year. Before when we had to have kids throw what was essentially their hardest tumbling we couldn't risk injury. Now the risk for injury is down, even with a much harder routine, simply because the tumbling is easier for them, relatively speaking. At ASC i talked to Orson and a few other coaches about this, and he said that some of his teams will run 6-8 full outs a practice until about a month away from NCA. His philosophy is that nothing builds stamina and consistency like running a routine. There's not a true way to replicate just how exhausting a routine is with everything going on, especially since in this day and age there is no such thing as just a tumbler or just a stunter. I tend to agree, and see many programs having success with running lots and lots of full outs. However, there's a catch. All of the athletes need to be able to do the tumbling without a lot of thought. If the muscle memory is there, the risk for injury is lower. For that reason I have my level 2 and 3 teams who are phenomenal tumblers for their level and who can do all of the skills in the routine out in the parking lot cold (not that i actually have them do it) run 2 or 3 more full outs a practice than the level 4 and 5 teams, who have solid skills but are not necessarily better 'at their level'. More time is spent on cleaning, choreo, and skill building with those teams.
However there are gyms out there who excel by doing only 1 or two full outs a practice. I wish I knew their secrets, but I figure it comes down to building your teams right and lots of conditioning.