Sport_Pilot,

I mean no disrespect but I think you are wrong.
An iron/steel setup does not have to temper, it has to anneal. You are removing milling and other stresses imposed by manufacture. The heating/cooling process is called heat cycling. The amount of time accumulated is not as important as how many heat cycles. Two minutes plus cooling produces one heat cycle. Two hours plus cooling produces one heat cycle.
And yes, as you smooth the surfaces and progressively increase RPM you DO go into two cycle, being careful to not run over-lean.
There are other ways of doing it but this process has served me well since the 1950's.
ABC, etc is a whole nother ball game. They do very little heat cycling. That's why they break in so fast.

George