In archery, repetitiveness is EVERYTHING.
Same anchor point, same release action, same grip on the bow, same follow through... it all comes down to the N'th degree of "little" things making the final result of accuracy achievable.
I made a test recently - I have two bows that I am going to hunt with this year - an older PSE and a new Bear.
I have a set of arrows for each bow that are different in length.
I have been shooting quite a bit and my groups are getting better - I have been out of bowhunting for almost 20 years - but I still was looking for any little thing that could make the shooting better.
I numbered each of my arrows 1 through 6 and then started recording, in a circle drawn on paper, where each arrow landed in relation to the bullseye.
For each group of 6, I marked them all out on paper... then shot again and marked again... etc.
At the end of my VERY FIRST practice session like this, a lot of things became crystal clear!!!
* almost every one of the arrows fell in the same sector of the target everytime, in that # 6 was always low and left, # 2 was always high, etc
* I began to recognize patterns, like when I shoot the Bear - I can always see # 5 corkscrew just a little bit... I knew I had one doing it - but now I know WHICH one...
* some arrows, for one reason or another, have very little hysteresis in them - in that they shoot in the same place, almost every time and are closest to the intended aim point
* it is VERY apparent which arrows to line up as your first, second and third choice for hunting... you KNOW which ones are the most accurate and the best choice to nock up when you get in the stand.
This does wonders for your confidence and helps you eliminate the arrows that could cost you a chance at a deer.
I guess the next logical step is to take a dozen arrows for each bow and identify the best 6 out of that dozen to use as your hunting arrows... I have basically just taken the 6 I am going to hunt with and determined which of these are the best out of that group.
I will state again - the traits of each individual arrow were incredibly apparent when you started charting them out like this... there was NO doubt!
Try this tip with your arrows and see if you can not drive some of the margin for error out of your shooting.
In closing, I will leave you with this: "In God we trust - all others bring data"... this is exactly what this process will allow you to do... effectively quantify the performance of each arrow.
Best of luck!