This is a technique (tearing deer hair rather than cutting butt sections) I had not seen before. Probably takes a bit of practice & tight thread wraps, but it does seem to have a nice finish for the Coastal Deer Hair Wing. Davie McPhail is well known in accomplished fly tying circles.  He has some very nice S-B-S tutorials. Haystack Emerger

Renowned Davie McPhail c/o HillendDabbler Blog