How detailed do your scenarios get? Do you have simple extrication or complicated multi-car extrication scenarios? Do your scenarios involve vehicles in any position other than on all 4 tires?
We do it in extracation class, we make everyone taking the class be IC at least once. they run the whole thing. We will help if needed but most of the time they do a good job. We will roll them over and sometimes have 2 cars involved.
Having scenarios that are outside of the ordinary (i.e. 1 or 2 cars, minimal entrapment, no unusual vehicle positions) is a good way to test SOPs/SOGs, TTP (Techniques, Tactics, and Procedures), and all personnel. Allowing the newer personnel to preform most of the work, to include IC (Safety always needs to be an experienced set of eyes, but having a tag-a-long for that position is good too), is a good way to see if training is being absorbed, what areas need to be trained on, and find new ideas that make things work safer, faster, and better.
We go all out we use Jersey barriers cars on dummies ontop of each other anyway thats real..I mean 90% of the drill is stabalization so it becomes second nature on the real thing
When we extracate we have the town highway stop by with a loader and smash the doors,roofs,and both ends in,then we postion the vehicles as to simulate a Head on,T-Bone,Car on its side,Car on roof,we have even put one on its roof in about a foot or so of water,another was a car into the side of a tanker truck,we put the car up to the side dumps of the FD tanker and crack open the side dump valves to simulate a haz-mat leak. These really make everyone think.We aslo critique these drills after over pizza and soft drinks(that gets them to stick around after drill and pick up as well as perticipate in the critique).