Most tuning guides you see say don't worry about how the nock hits the target only its position compared to a fletched arrow. This method only says to look at the bareshaft in flight. I tried this and it works very well. My arrow responded to cutting down and I didnt have to worry about consistency in shooting to determine weak/stiff. I could short draw with my final arrow and it would show stiff. Overdraw and it showed weak. Think I am very close.
https://www.youtube.com/watch?v=BSJ6-HjPMTM
That's how I tune my arrows. Works great and easy to get owrfect flight. Has mine hitting the same at 25 yards and flying like lazers and judging once it hits the target defiantly throws me off if I tune like that.