****zu, good post and always good for a timely reminder. I drill my students, and I think most other instructors do the same regarding the use of transponders.
I think the problem is more of dodgy transponders than anything. In recent times I have flown aircraft with transponders whos knobs fall off, stiff to turn, the OFF SBY ON & ALT markings are either faded or worn off. Others, to be set on ALT, the knob index had to be turned 90 deg past the ALT detent. Got it working by trial and error.
Oh the joys of slipping into the seat to find in the instrument panel one of those flash Garmin transponders, you know, the ones with the numeric keys along the bottom of the unit. Was like a kid with a new toy........ and it even has a count up, or count down clock. Neato!!!