"...sustained lead makes the use of a light gun much more controlled than the swing through method. "

No arguement from me here. I totally agree. But the quail rarely cooperate, where I hunt, to allow for enough of a shooting window for a sustained lead. Hence the result, low percentage shots, low take, high amount of fun. When I shoot dove, sustained works for me and my light, whippy guns or heavy guns alike. But I can't call what happens with the quail in the steep hills and thick cover where I hunt; sustained lead, short or otherwise.