In answer to the original question. For myself, and most of my bows and shooting right handed with my deer target pointing left, from 15 yards out about 30 yards the where top of the arrow of the arrow shaft meets the bow, the secondary is even from the front hoof on level ground from the back of the hoof to about 6 inches in, depending on the bow. T
he shot is more or less instinctive.
After that the arrow comes up on the target rather quickly to the point on which is 55 to 64 yards depending on the bow and the shot is more or less using the secondary. I developed the secondary using the arrow where it meets the bow by habit of cutting most of my blunts and target arrow to net length, now if I use longer arrows or broadheads I still use the same aiming point,in secondary sight, to keep from getting myself second guessing my aim. I really don't like shooting at deer more than 30 yards away, When I did with a longbow I thought the deer was closer and the arrow still found the mark. I think for many with lots of practice at longer shots it may start out a gap or secondary aiming method, but it gets more instinctive with time.