Shock cooling is a myth according to some US experts on engine handling. Bob Hoover uses a standard Aero Commander for his high speed engine feathered loops and there is no shortage of owners to lend him their aircraft. Heavy rain cools the front cylinders dramatically, but one did not hear of DC3's and Catalinas falling out of the sky with shock cooled Pratt and Whitneys. In any case, at the low speeds used in Cessna 152's for gliding, shock cooling does not exist. It is my understanding that there has been no specific proof from measured tests that cylinder cracking has been caused specifically by shock cooling.
During the war years around 10,000 Tiger Moths were produced for training military pilots - and for aero clubs after the war. In those days the standard circuit always concluded in a full glide approach, where the throttle was set to idle on base leg (depending on wind) and not touched (unless undershooting, of course)
The RAAF certainly did not have Moths falling from the sky due cracked cylinders.
Re approach and landings in Cessna 152 and similar types. The approach speeds are similar to the Tiger and Chipmunk. Forget 1700rpm on base. That just complicates things. Hold level flight at 1000 agl on base until you judge you can get in without flaps, then close the throttle completely and glide using flap as required. Cross the fence at 54 knots (not 60 knots which gives excessive and unwanted float, let alone tendency to balloon). The Cessna POH states that normal landing approaches can be made with power-on or power-off. So obviously so called shock cooling is not an issue as far as the manufacturer is concerned. Glide approaches (if taught correctly) require only basic handling skills. Many present day schools teach glide approaches from a downwind position which requires cutting corners. This was never the original concept of glide approaches to land in circuit training. Certainly, students taught glide approaches as the norm in Tigers and Chippies, usually soloed in half the time that you see nowadays. Circuits were tighter because instructors insisted upon it. None of these huge money earning circuits taught as the normal procedure today. Much fewer bull-sh.t cockpit drills certainly helped too.