One of my pet peeves about flight training is that the engine failure scenario taught is in fact the statistically least likely scenario. A complete failure with no warning and an unsuccessful attempt to restore power. This is IMO exacerbated by the student knowing that the instructor will tell him the restart is unsuccessful so that they can complete the forced approach.
This is IMO very negative training as it it minimizes the importance of the cause check which in the real world has a significant chance of restoring power as the reason the engine failed was pilot induced
Similarly partial power loss scenarios are virtually never practiced but are in fact much more likely to occur than a full power loss. One of my favourite exercises is to reduce power to a level that provides just enough power to maintain level flight at a speed around best endurance and then ask what the student is going to do.This invariably results by a blank look from the student but leads to a very good pilot decision making exercise with some directed questions.