At the flying schools I teach at we have had no problems with a/c not reaching their TBO's, depite the (relatively) rough handling they are subjected to; lots of power changes, PFL practices, start up and shut downs at least 6X a day. Compare this to most of the private operators at the airfields, who seem to have no end of problems. I feel this is down to under-use rather than the way the a/c are operated.
Private a/c have an easier life as they are generally operated for longer flights, have less take offs and landings, less hard landings(though this may not always be the case!!) just as much maintenance support and are just generally treated better than you average club hack.
Despite this I know of at least 6 a/c at my home field that didn't get anywhere near their TBO's. I know the guy's who fly them and they are not muppets who handle the engine badly, and yet they have had major problems.
I always think that we over emphasise on certain areas such as 'shock' cooling and ignore many of the more serious issues, such as corrosion due to under use, that affect far more people than a relatively unproven 'problem' that is shock cooling on a light a/c used 'normally.'