My fit procedure, carried out a few years ago, consisted of reading articles like the one referenced above, and discussing things on threads here, then doing careful experiments. I got an adjustable stem, for example, and I could try a particular handlebar location on a 60 mile ride, and then make a small (as in 5 mm) adjustment based on how it felt.

I was only interested in comfort, and it was a matter of adjusting things until all neck, shoulder, butt, arm, and wrist discomfort went away. I was successful in that I've gone for centuries with no pain [get it?].

Trying for maximum efficiency is an entirely different matter, and more difficult to measure.