Machinist confuses the hell out of me

[Zojha]

I can clarify on the "tick" at least:

A "tick" is when the server actually applies things like DoT damage (That gets applied every 3 seconds) or in this case heat increase from flamethrower. Flamethrower will tick multiple times and apply heat with each, but since it's a DPS loss to hold, you only want it to tick once to enter overheat. If you cancel the skill before the "tick", the server won't have applied the heat yet and you won't enter overheat with it, wasting time and the CD.

How long it takes for a "tick" to happen in practice can vary a bit. In effect, that means that you build up heat until only one heat tick from flamethrower is required, then hold it until that tick happens.