There are many different break in methods...and people just tend to stick to the way that they have always done it..."if it aint broke dont fix it".

A couple of things that I do are...
Feel the pinch- how tight the engine is to turn over....when it is warm you will notice that it becomes easier to turn over as you run more fuel through it...this can give an indication of when you can start running harder/leaning the mixture.
Also I mark the flywheel with a marker pen or a scratch so that I have a visual reference of where BDC (bottom dead centre (piston position)) is and always line up the mark when I stop the engine.

Heating the engine is a good thing to do...not only when the engine is new but for every cold start...when the engine is cold then the pinch is tight, warming it helps to relieve stress/wear and will make it last longer.