I've been to tumbling clinics. I don't go to the stunting ones normally, cos I find they're more for flyers. I've done everything from level 2 to level 4. Some have been all drills and no spotting for skills, and others have been 5-10 stations with 2-3 being for spotting. It all depends on who is running the clinic and their philosophy.
Personally, I prefer the spotting. I normally go in with specific skills I've been working on for a while already. I've done the drills and I'm close to getting the skill, so I want a fresh pair of eyes on it to give me tips/corrections to get the skill. I've only been to 1-2 clinics where I didn't get a new skill. I'm not too big on trying new things cos 1. I know I'm only going to get introduced to it and won't have enough time there to get some serious work done, and 2. I prefer to try new things into the pit so I don't have to worry about crashing and burning. I can just focus on trying to get the feel for the skill.
Please remember that I'm old and I'm working on very specific skills that I know I have the potential to get. I fully believe younger kids should get introduced to new skills and work their way up the progressions/levels.