Instructors training techniques all vary in my experience , the good instructors leave an indelible mark on you a long time after you've gained your licence , when things have got challenging in the cockpit , bad weather ,icing , rough running engine etc, there voice sometimes rings loud in your ears when you need it most ! I'm not sure of the wisdom of turning the fuel off even at 3000ft in glide range of the field ,poor airmanship shouts at me ! . I had an experience a few years ago with an instructor in California , night flight from las vagas to San Diego in a beech duchess the weather in palomar was fog 1500 meters vis low ceiling tops at about 4000ft ( not unusual in Feb) the airport is surrounded by high ground up to 5000 ft , last but one flight of an intense IR course with what I still view was an excellent instructor , but whom I realised at that point went a bit to far , as we were about to turn inbound on the procedure above cloud he reached to pull the right mixture leaver to idle cut off , I asked politely in a loud voice "don't do it " too late the the starboard engine ground to a halt ! yes I did the drills as taught yes I flew the approach on one engine to minimums and landed safely . What did I learn ? I had been trained very well , I gained confidence in my ability ...... I also learned that instructors even good ones can make very bad decisions, had we gone missed on the approach we could not get out of the situation as the climb performance on a duchess single engine is bad at best, instructors Have no right to play with your life! training should be done in as safer manner as possible , my advice get another instructor !