I can go along- just- with the idea of stopping the engine during the AFI course. I would prefer to do that at altitude, preferably wearing parachutes. I've had too many experiences of a warm Lycoming refusing to start, to want to try that in the air. Embarrassment I can cope with, but I don't want the AAIB to ever know mmy name!
And with all due respect to CFI, if anyone ever gives me an EFATO in a single with the mixture control instead of the throttle, the test is over, I'm treating it as a real emergency- and when I get on the ground, I'm phoning the CAA. Oh, and I won't be paying for the flight, either!