As most others have said,
Flying Cessna 152 / 150, I was taught 10 seconds burst of carb heat on downwind checks (unless evidence of icing, in which case leave it on) and then carb heat on when setting up for descent before reducing the throttle. Carb heat to cold at 300' on short final in case full power was required for a go-around.
I was also taught that carb heat should always be on when the engine RPM is below the green or if it is drizzling or raining.
On top of this the engine should be warmed during glide approaches or PFLs. Just my 2ps worth.
F - Wyg