My thoughts on this-- Comfort is job one---You do not want tension anywhere--- nice relaxed form is paramount to good shooting habits and accuracy. So altho sometimes my customers may in fact be "off" according to "perfect drawlength", I usually overlook that a bit if I see the person is holding very steady and they say that is where it feels good and they are comfortable. "Perfect drawlength" IMHO is as individualistic as the setups themselves, due to each individuals' stature, so at the shop I maintain a close eye on steadiness of hold and correct alignment and form, moreso than I do "perfect" drawlength.
Exactly - that's why I wanted to try the "Genesis with measured arrow" concept - not to see what each person's "textbook" draw length was, but to measure their most comfortable and stable drawlength. If I went with what I told was my exact draw length when I first got into archery, I would be shooting a 28" DL. I shoot a 29.5" DL and a 1/2" string loop very well. It just feels better to me, therefore I am able to hold steady - and I am much more accurate!