Paul, I agree that as a turbine takes time to spool down, there is a lot of assistance in simulated engine failures. But some machines with high intertia blades are very forgiving.
I remember doing a practice auto in a B206 and to our surprise the needle was barely touching bottom of the green even with collective full down. It was intended to be a hover recovery but my instructor was so absorbed by the phenomenon I ended up doing a full touchdown anyway. We later found out that the pitch links were actually off and had to be re-adjusted by the engineers.
Another instructor once demonstrated a practice auto in a B47G (piston). He took off vertically to 200 ft, then rolled throttle off and let the chopper drop vertically all the way until perhaps 20 ft AGL when he pitched collective, and the descent of the machine suddenly slowed down, as if a lift (or elevator) is just arriving at the chosen floor. The rest is continuing to cushion the touchdown with collective and landing at the very point we took off. Shows how much intertia there is in the ol' girl's blades - amazing stuff.