and MAKE SURE that the engine is warmed a minimum of every 500 feet. during the descent.
A bit of an over-kill, maybe? The reason for application of high power recommended during a prolonged glide such as practice PFL from altitude, is not to keep the engine "warm" but to burn off any lead deposits from the spark plugs so that full power is available for the go-around.
Melting of carb ice may well be a spin-off from the plug clearing exercise. But to conduct this operation as a "minimum" every 500 feet means the PFL is a waste of time as glide practice is minimal since the nose has to be raised in order to maintain correct gliding speed every time the throttle is advanced to high power.