It would be very helpful and informative to know just what the measured difference in point of impact was that you have found with these variations in spine deflection. Also did you find a pattern in point of impact differences to spine difference (weaker spine high, low, left or right)?
Unfortunately, I wasn't detailing any of that. If I had a confirmed flyer, I culled it. I number my arrows as i build them, and note what the spine variation is, but I don't record the actual numbers, or where they hit. That would take more work then I really want to do. I have also planned on building a few dozen where I align the cock feather with identically spined sides (not necessarily the stiffest side), and see how they fly. I haven't done it yet, because what I'm doing is working so well, I don't want to have to refletch a dozen. I'll have to get overcome that laziness and give it a try. If I have a spine of .340 on a dozen and I find one that is .370 on the stiff side, I cull it without shooting it. Once they get to the weak side, they just don't fly the same with broadheads. I'll save them up for someone shooting 55-60 lbs and give it to them.