There is one thing I teach all of my students. Tune the engine so that you see a slight trail of smoke behind it as you fly. When you do this it's running slightly rich. If you tune your engines to this point it's a good bet that the engines will experience a very long a productive life. It only takes one lean run to absolutely cook and engine and ruin it. I've seen guys on the line chasing that elusive "perfect" tune, only to get an engine too lean and burn it up in the air. As Mike pointed out, the racing guys know that their engines have a short lifespan, but they accept that as part of the sport. You may lose a few hundred RPM, but keeping the engine a tad bit rich will keep that engine running for a long time.

Ken