The dense hackle on some American wet flies is there for a reason. As was explained to me by the owner of our local fly shop, the flies are at times fished very deeply, and the hackle traps air bubbles, making the fly work as a deep caddis pupa or larva pattern. He swears by this. I think several of us are talking about different things here, different applications. If you're just talking soft hackles, then I could see the larger partridge or other game hackle extending to the bend of the hook, but with winged wets it's more common to just take the hackle to around the point of the hook. Alice Conba's flies exhibit this, as do most American wet flies with the exception of Helen Shaw's. In any case, I've never used a hackle gauge, just measure barb lenth at the fly. Nice to have a ballpark though, even though none of us agrees what it should be.