How does the engine know the
difference between ground runs at, say 2000 RPM (run-up speed on our
plane) and an extended descent? Is *that* "bad" for the engine, too?

I'm guessing, but in an extended descent, the engine was already running
full bore for a while and is nice and hot and happy. In a ground run,
the engine probably started out cold and never got hot and happy.

Jose
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