The problem with those examples, Bookworm, is that none of them pertain to FL's situation, ie a glide approach to a full stop landing.
Questions as to whether the engine will restart before touchdown, or whether the student will shut down the other engine are irrelevant when the intention is to land a SE aircraft with the engine shut down.
I would argue that an experienced instructor in a simple aircraft should be able to perform an engine off landing onto a reasonably sized airfield with a 100% success rate. Students who have been taught to do the same will be a lot more confident & capable of coping with a real engine failure.
I learnt at a reasonably busy airfield, all my 'glide' approaches were with the engine running. It would have been nice to do a few engine off glide approaches.