I have never quite understood the differences between gap, secondary sighting alla Howard Hill, and point of aim. The old point of aim target style was to have a definite marker, gap was a space picture,(startrek?), and Hill's IMAGINARY secondary aiming point. I have a feeling that Hill described what one's own hand/eye computer does in the shooting process, with giving some conscious acknowledgement to the arrow. The other day I was teaching a kid to shoot. He had form but no aim. He was trying to hard and looking at the arrow and not the target, he was trying to cheat. I taped two match sticks on the bow to match his cant and told him the target is somewhere in between those match sticks, but both match sticks are wrong, so don't look at them. Then he could hit, I took off the bottom stick and he still could hit, then the top one and he immediately shot high, hit my garage. So I played the point the pvc pipe game, he points at stuff without looking, I look through the pipe to tell him where to move it. He argued with me at every object. When we went back to shooting he could hit within a few inches of the dandelions that I stuck in the target.
A short cut to developing second nature aiming. If things start going awry, we can always go back to secondary aiming fundamentals.