This looks to me, with the exception of the cutting off of the tip of the feather, which I don't understand, to be the method that has been used for hundreds of years to make a partridge collar on a fly. If there's another method, I'd rather not know about it. I'm too old at this point to change.

Actually, Hans Weilenmann has a cool way of doing it tying in the butt with the feather extending out over the eye concave side up, before you do anything else. You strip off one side of the hackle before tying the feather on, and it's easy to get the wrong side stripped if you're not thinking. It makes a really sparse collar, but I'm too set in my ways to do his version either. I do use it on soft hackles though when I think about it.