Yes, I train/trained at Quantum and when conditions are not conducive, carb heat is always down and locked.
Ehm. Am I too rusty in my theory already having not flown (helis) for some time? Maybe. 'Down and locked' meaning as not using it?
If you have high OAT, it's not about 'carb icing conditions' but about collective fairly low/not pulling much according to MP. So risk of carburetor butterfly icing due to low dynamic pressure (=lower temp in throat)
EDIT: I don't think anybody's contradicting other's training.
Descent to final = having carb heat applied (and lowered for last 50-70ft alt, depending)