That was a good read pf. my pratical experience emulated your theory..... so the theory must be correct!.
With my speed 3 there is a magical point of letting the bar out... about 1/3 when jumping. When i find that magical spot i glide A LOT longer!.
On the inflatables that point is far less obvious.
Exactly, your "feel" is absolutely correct - especially because I did not mention, that when you fly with either headwinds, or diagonal headwinds as we most often do in a "kiteglide" - you have to fly at an even lower AOA for max glide (because you need more speed to get the furthest forward, eventhough you decrease L/D), meaning you have to sheet out even further precisely as you say.
So the reason one sheets out is because max L/D happens at a lower AOA than max hangtime, but also because if you have partly headwinds, you need to decrease the AOA even further and under max L/D to get max glide