I'm no expert at this but I'll give it my best.

Projectice physics are pretty universal. If you're familiar with rifle shooting basics, think of it like setting up a scope/rifle for MPBR.

Here's something typical for a deer rifle (purely hypothetical & rough):

0 yards = -1.5"

25 yards = 0

100 yards = +3"

200 yards = 0

250 yards = -3"

MPBR = 250 yards.

For gap shooting with one of my bows, I'd see something like:

0 = 0 (don't try it, though)

10 yards = +9"

15 yards = +12"

20 yards = +8"

25 yards = 0

30 yards = -10"

There are always two zeros as the arc of the projectile trajectory crosses the line of sight. For a rifle, it's further out since the sights are elevated. For a bow, the first zero is at the "muzzle" since it's the arrow itself that is the front sight.

As mentioned, Blackmon's video on the gap compromise is great. There are a number of things you can do to lower the arc of trajectory, or even just the perception of it. Anchor points & arrow length both cause a change in the angle between your eye, the arrow tip and the nock. The sharper the angle, the flatter the trajectory at closer distances (low gap variance). The wider the angle, the greater the variance in your gaps at these ranges. You can adjust the angle by anchoring higher and/or having longer arrows.

Then you can also make your arrows lighter or heavier to adjust the speed. Lighter arrows will show larger gaps but will have lower variance in those gaps over distance. Heavier arrows will have smaller gaps but a greater variance in the gaps.

The best thing I ever experienced for keeping small gaps is long arrows. Last year, I moved to a shorter bow that I prefer for hunting. But putting 32" arrows into a bow quiver that's mounted on a 50" bow gives up a lot of the advantage of that 50" bow (lower limb clearance). So I went with very heavy, short arrows as a compromise to keep the gaps within reason.

Much over 10" or so, gaps become more difficult for me to estimate -- especially on smaller targets like turkeys. I can picture a handspan width on just about any target but 20" or 30" is a lot harder. The point of the arrow is somewhere in the dirt. Blackmon also put out a more recent video showing how to gap at the riser using a little cheater mark to set the vertical gap. While it may or may not be legal for competitions, it's proven its value at my home range. I put a little white line on the riser that I can see at full draw that sets the vertical gap at about 19 yards. So from 10-22 yards, I'm +/- 3", assuming I did everything else right (not always a safe assumption).

Hope that helps a little.