For most people it's just adding less weight. I'd venture that if you can't hang BW two armed from a one joint edge then there's probably better training to spend your time on. One armed generally will need a pulley for non beasts.
Reducing time is impractical I'd imagine, the margin in loading and unloading a hang, and judging the start and end point, is easily a second, which is more than say, 10% of a 7s hang.