Is there any downside whatsoever (other than a slight reduction in power) of having the carb heat on upon entering the pattern and leaving it on all the way till short final every time regardless of air moisture/temps?
I ask because back in the day when i was training one instructor advised to put carb heat on on the downwind to "test" to see if it was needed and if not return it to cold, another said just leave it on till just prior to touchdown or go around.
Its pretty hard to expect a pilot to have a mental picture of that carb icing envelope chart in his head and decide if conditions apply, so why no just leave it on all the way round?