If your airfleet is large and diverse, it's no use remembering the numbers (except maybe the pedals which are stiffer), because all the seats will have different levels of wear, and will be more or less "packed".
My method is to put the seat fully down, then move it up until the weight of my feet and legs are supported half by the seat and half by the feet (from 100% on the feet at the beginning). Then I like to have the armrest rather flat, so tilt it flat and up (which gives something like B3 usually but I don't set this number as a goal either). Then the backrest should give some support but still be comfortable.