I don't know if someone mentioned this before (couldn't search) or not. But here it goes. In the chapter were Isshin appears as a shinigami he mentions that skilled shinigami can control the size of their zanpaktou, so they don't walk around with zanpaktous like scyscrapers. Just now I was thinking that Gin's shikai is that he can lengthen the blade to make it "shot" out. To my theory. Couldn't all skilled shinigami control their zanpaktou to act like Gin's shikai abillity and shot out by will?