Haven't used one, but the easiest (and cheapest) is just to blank bale. Which, if you have a good target, can even be done inside. I use a curtain, but a block target set against a garage or basement wall is fine. All you do is concentrate on what YOU'RE doing, and being so close you needn't worry about missing. With the weather as bad as it is, this is a real plus for me. I get to keep shooting and I ingrain the shot sequence into my mind by not thinking about accuracy but the entire shot itself.
Same goes for making changes in you shot sequence such as adjusting anchor or whatever. By the time you have it ingrained by blank baling you get to see the real effects it would have on your accuracy because it's already a natural part of the process. Alot of the masters of the longbow out there, and in the past, have done this: Howard Hill, Byron Ferguson, John Shulz, etc. It's hard to bring yourself to shoot and not think about accuracy, but once you do you'll be able practice alot better.
