I know indoor spot shooters who play around with arrow length and weight, then their anchor points, until they get their point-on distance exactly 20 yards. Longer, heavier arrows shorten the point-on distance while shorter, lighter arrows increase it. Higher anchor points shorten point-on, lower anchor points increase it.

You're right about getting the correct arrows. The charts will get you in the ballpark, but you still have to try at least two sizes each side of the ones the chart recommends. So, you're going to shoot at least 5 different shafts in order to find the magic one. And then you can fine tune the arrow spine by playing around with brace height. Of course, with compounds it's easy. You simply adjust your poundage to fit the arrow.

When I was shooting field archery, I adjusted everything till my point-on was 50 yards and I had my gaps figured off of that. Anything 30 yards and under, the gaps were so big they were practically useless, so I shot those distances 'instinctive'. The gaps really helped put me on target from 40 yards on out.