Bob,
To your point about the variation in insect wing positioning. Take this close-up of a Western Green Drake, for example.
Now, if you were to draw a vertical line from the wing tip to the body/hook shank, at what point of the hook shank would a vertical wing be tied down to get to the same point at the tips of the wing? Seems like it would be be at a point less than 2/3 of the hook shank............unless you were to tie a yarn wing and cut the wing at an angle with the longest fibers at the rear of the wing????