Paul,
Very good post, Thank you!

What type of release and rest are you using?

I tried a similar test with CXL2's recently. I left them full length so that they should be way underspined. OT2 shows that27" is correct length for my set up. Both fletched and unfletched were hitting the same POI at 20 and 30 yards. This was with a hinge release and a launcher blade rest.

One reason that I'm not getting different POI's is that my bow is a shoot through, Nitrous X system. Maybe the lack of the torque of a cable guard affects the results?

I agree that properly spined arrows are the best for accuracy and forgiveness. However, I haven't figured out a shooting test for carbon arrowsto prove that the spine is correct or what adjustments are needed.

Finger shooters have this bare shaft planing test, what do release shooters use to adjust spine?

Thanks for posting this!