I used to do the same with the carb heat, but a closer look at the Cessna POH shows the carb heat should be pulled when power is reduced for landing and not put to cold until just prior to shut down (or in some cases after landing). If a go around is needed, the carb heat is put to cold at that time.
Dusty surfaces need to have the carb heat in the filter position of course.
In Alaska in the winter you will lose your engine in a C150 if you don't follow this procedure. You should set full power for takeoff with the carb heat HOT, and only go to COLD when the engine is up to speed and running smoothly. With the carb heat in COLD you often will not even be able to get the engine to accelerate, and it will die when the throttle is opened.
If you have the carb heat cold the engine will die when you close the throttle on final for the landing and you cannot guarantee that it will start again to taxy off the runway. The Cessna 172 does much better, but the procedure seems good for both types.
The DHC2 on the other hand seems quite happy if the carb heat is set to COLD for takeoff and set to COLD again on short final.
Point is that the POH should tell you what to do and an instructor should be careful when teaching contrary to that. This includes setting flap in a turn, which so far as I have read is not restricted in the POH.