News to me Byron. I've never read this before and generally leave the post about hook length long, just as I would on a Catskill.
Before coming into work, I pulled a few books and checked some vids.
AK Best ties in his turkey T-Base wings what looks to be hook length long. Randall Kaufmann ties his calf tail post about hook length long as well. In one of his vids, Davie McPhail suggests tying a CDC wing post between hook length and hook shank long. Art Sheck ties in a polypro post that's shank length. Charlie Craven uses hi-viz that's shank length.
There's a Gulper Special FOTW tutorial here at FAOL written by Dave Hughes in which he suggests the post be shank length.
Over the last couple of seasons, if I'm fishing a may fly pattern, it's most likely going to be a parachute with wonderwings hook length in size.