Chuck, I totally agree.
Our club twin suffered very early wear and had both lycomings swapped around 1300hrs!
Our club SOP is now not to feather an engine more than once in training. This is the legal minimum for JAR MEP. We are asked not to do it any other time to avoid excessive engine wear.
I do believe that the student should see the prop stopped at least once though. Do you remember the first time you did it? I do, I nearly crapped myself! So there is a good teaching point to see it once. I also whilst on one engine get the student to do steep turns and very gentle wing overs. It teaches them power/rudder control and also that you can still fly a twin single either way provided you keep the speed up and know the supplementary recovery procedure (close both throttles!).
Not only do we stop unnecessary feathers, but we also simulate a failed engine by initially closing the mixture lever. Once the student has identified and verified by closing the throttle, we then advance the mixture to rich. All done at safe height. In the circuit we try and use the throttle instead. According to Lycoming, this method of using mixture stops excessive forces and wear on the crankshaft as the power is rapidly reduced. And can stop the crankshaft becoming de-balanced.
W. Collins.
I feel very sorry for your Aztec! I would have delayed the test flight till another day unless it was actually really necessary! But hey, its your aircraft! For info, our club Arrow suffered cracked cylinders early on with a new engine, due to "someone" descending the aircraft at probably idle power from high altitude. Nobody could be blamed tho. And incidently, in a PA46 malibu, if you reduce power by more than 3inches manifold at high altitiude (25,000) you will cause damage! The front cylinders are operating at a very differnent temp to the rear ones! All being boosted by two turbos.