Funny how people still go on about shock cooling. If you read articles by people who have spent time looking into it (e.g. Barry Schiff), there is no issue as long as CHTs are below 380 F. Maybe if you run really hot, like 450, there could be a problem. But it's really a bad idea anyway. Current thinking is you should stay below 400, and certainly below 420.
Once you reduce power for a descent, the CHTs will be below 380 so it becomes a non-issue. The idea that pulling power just before landing will damage the engine has no basis in fact.
It happens that my aerobatic instructor still worries about it, so have to nurse the engine into the glide (my rule is, if the owner of the aircraft wants to worry about something, you should too, even if you don't really believe it). But even so, every single landing we do in the Pitts is power off from pattern altitude.
A few years ago a couple of guys killed themselves because they believed it would harm the engine (a big radial) to pull the power completely. So they overshot the runway. I'm sure that did a lot more damage to the engine.