Agree, this is quite mundane stuff yet the the source of so much angst and BS on the flightdeck that could be so easily avoided. But in all seriousness, it's like studying the principles of an ILS. Boring, boring stuff but that one time you capture a false glideslope or try to intercept outside of the rated range and "weird stuff" starts happening, the mundane effort paid off. Recognition of the situation is quicker.
(As I type am thinking didn't CX have a 777 (??) incident into RUH not too long ago due false glideslope??)
My notes at hand on use of the word "heavy" are as follows:
On first contact with the TERMINAL RADAR AREA prefix the callsign with "HEAVY". The ICAO standard is for any aircraft taking off with a gross weight of 300,000 lbs (140,000 kgs) or more to use the term "heavy" in radio communications BELOW 18,000 ft AMSL. In the US, the threshold for "heavy" is 225,001 lbs (115,700 kgs) or more. The term HEAVY may be omitted after initial contact with ATC.
So you identify your wake turb category on first contact with radar / ATC and only use it below 18,000 ft. No need to be "check'in in witch-a twenny one nine, thirty six thou, United 123 HEAVY" every transfer or every call in cruise. (Let alone like that [exaggerated?] method anyway...!)
My point is, it's but one of many, many habits adopted and not a procedure learned.
If incorrect then I'd appreciate the feedback.