I had to print out his whole thing and bind it and take it outside when I started using OL's guide (which OL's quick to point out has been around for years and is not "his" but he made it all available in clear simple language)
Remember to do to the bare what you do to the fletched...and vice versa. As noted above, it's all about "difference between fletched (which correct some of the spine errors) and those bare which demonstrate the error...
as you progress, changing slightly one thing or another, your two come closer together.
I've not read it in a while but I don't recall 4" being "close". I had mine grouping maybe 1-2" low/right. Fletch stiffens (effect) and then once you have them hitting the same relative place, then you fletch em all, put broadheads on the one half of whole fletched kabootle and start testing again... till they all hit dead nuts!
You have to really take some time, read the website or like I did, print it and study it... then the subtleties start to come out!
It's not that hard... just takes time. And don't forget, the amount of center shot can make a ton of difference. OL shared that on the ole berger button, 1/32" made a huge diff... As does adding a tip protector, silencers to string or a bow quiver...all affects harmonics and tuning! Do it after the bow is set up the way you want to hunt or shoot it.
thinning the sideplate or adding material can do as much as changing arrow length or tip weight!
Go read it and have some fun!