the power requirements for a normal circuit have allowed the engine to cool down from cruise power and taking power off further for a glide approach is going to make little difference. Especially as the nature of a glide is no different from the taxi back to the ramp.
On a warm summer day, agreed. Though, lets remind ourselves that the power to fly the "normal" circuit, could in many cases be about cruise power - which does not really afford the engine much opportunity to begin to gently cool down.
So, when it's minus millions out (well for my flying, I begin to think of things as getting cold at -25C), The nature of a glide is very much different to that of taxiing in as it affects engine cooling! The glide will be at let's say four to five times? the airspeed of taxiing? That's a lot of cooling in the glide, compared to the ground (depending upon how you taxi!). When the engine stops developing power, it stops developing most of it's heat. But if you're still flying, you're still cooling. Too much cooling all of a sudden is very bad for the cylinders.
On the 6000 foot runway, where I fly to work a few days a week, I amuse myself sometimes with partial power takeoffs, and high power landings, in the mighty C 150. With full power RPM being 2750, I have quite happly gotten airborne and "climbed out" with 2100 RPM, and landed with no less than 1900 'till I had all three wheels on.
Aside from skill development, there's no real need or benifit for these odd power settings. But I did find the skills useful when I was required to do partial power take offs in the Caravan for the purpose of takeoff distance data gathering, and a high power landing in it, so as to be extremely gentle with an unintended "object hanging loose beneath the aircraft" situation.