Returning briefly to the carb heat thing, my initial PPL(A) training taught me to put carb heat away on the ground after landing, or immediately after throttle fully open for a go-around.
Learning to fly helicopters in Australia, the only time I really touched the carb heat ( this is in an R22 ) was during the power checks. Converting my Australian PPL(H) to a UK one, the school I went to teach ( as per R22 POH ) full carb heat below 18" MP, and no carb heat below 200' on finals - it makes a considerable power difference ( I've seen up to 1.5" MP ) if you're a fat b***ard like me.
Personally I'd have like to have been taought correct use of carby heat in Aus - even though in Sydney temperatures rarely dip to the point of needing it, go flying in the Snowy Mountains and it's a different ball game - last thing you want is an ice-induced engine failure !!