Can we agree that idle power/full power engine management will cause
more wear and tear (AKA: "Damage") to an engine than steady-state
operation?

No. Why?

I'm no thermodynamist, but I believe it's commonly accepted that
taking an internal combustion engine from steady state/low RPMs to
full power/high RPMs (as one would repeatedly do during touch & goes
and engine-out practice) is more harmful to the engine than simply
steady-state/mid-RPM power settings.

A rough analogy would be to think of drag racers versus rally car
engines. One lasts 20 to 30 seconds, the other lasts 1000 miles.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"