T'aint,
my instructor would every now and again gently cut throttle on me while my hand was off the collective (dialling in the ATIS or whatever). He would also do it at night at the end of a nav-ex when I was tired and my guard was maybe lower than it should be. On hearing the horn he'd expect me to have the lever down well inside 2 seconds. The entry would always be messier than a 'HASEL' auto but it did teach good reflexes (Pavlov's dogs springs to mind). Once entered the auto would then be aborted more or less straight away. It was the entry he was worried about and not so much the rest. Like you, he firmly believed in the importance of polishing both ends. Do you ever do anything similar with your students?
Irlandés