To comply with this we apply carby heat on downwind and make sure there is no icing then leave it cold on the approach.
Agreed however; on a Glide approach you do put the Carb Heat to Hot and in all my experience of teaching on the PA28 you select it back to Cold at about 300 feet so that it is not forgotten for the low go around. If you go around at 301 feet and forget, it really doesn't matter! I seem to recall this was even in a CAA approved expanded checklist for CPL skill tests.