Boy has this topic ever wondered from subject to subject. It started with a question on shock cooling, covered ROP-LOP, POH v.s. GAMI/American Pilot, engine temperatures, throttle management, percentage power, and mooney mpg effeciency. I'll add a couple of thoughts but I won't quote my POH or Braly, just thoughts, or maybe better expressed as my philosophy based on reading many sources and boiling it down.
The critical temperature for aluminum is about 350 degrees. Above that temperature it starts losing strength. Somewhere north 400 the effect gets serious, 450 is excessive (my opinion). I like 380 as a target for max CHT and start making adjustments to cool things down when any cylindar exceeds that. For my engine, TSIO360LB in a 231, I don't worry about shock cooling. I just plain don't believe it is a factor for CHT's below 350. If I start under 380 I'll be under 350 before I get a 30 degree drop. On the other hand if I started at 450 I might be concerned about sudden changes.
For the record: I have both feet planted firmly in the WOTLOP camp. Big pull to lean early when climbing to altitude and stay lean until I start my descent by leaning agressively, way before I start reducing MP. By the time I start reducing MP my CHTs are 320 or below. Shock what? My engineis already cool. Also I don't mind running a tank until it's dry. Hows that work out for shock cooling... WOT cruise fuel set to stay under 380, then out of fuel until I switch tanks. My JPI doesn't show much CHTchange, not enought to cause concern. Understand, I am not suggesting anyone else should run their engine this way but it works for me.