If you can quickly reach the victim, a live-bait rescue takes very little time to set-up. Basically, set-up is connecting a line to a rescue vest, ensuring the belay person/s are ready, getting someone downstream quickly for safety, and away you go. Simple and effective. If the person is panicking, this can be a very dangerous rescue method. A simple rope toss in that case is a far better solution. Here is a decent article on the risks involved: Panicking Swimmer.