Form work is a short range proposition...really short, like 3-4 yards. The reason for that is you are NOT working on accuracy, only form. Will it help your accuracy, generally yes because it will improve your consistency.
I like to work on accuracy by shooting 25-30 yards. This makes 15 yard shots look like a slam dunk. Like O-G mentioned, I seem to shoot better at a distance do to better concentration. The key is to move that concentration forward with you.
For hunting accuracy though, I think it's best to vary the distance. That's why many here will recommend stump shooting at targets of opportunity. It helps you learn the trajectory of your bow and to estimate distance. I still think 15 yards is a good distance for shots on game like whitetails. It has been my experience, though, that whitetails don't always cooperate, so I've had to shoot them at ranges from about 14 to 22 yards or so. I've passed on closer shots that just didn't feel right. I've also passed on shots at 30 yards that I am capable of making because I don't trust deer. Stationary targets aren't especially difficult at 30 yards, but deer can move a long ways in the time it takes an arrow to travel 30 yards. It's not worth the risk of injuring a game animal.
So practice at a variety of ranges, then set your own limits on what you think is an ethical shot and stick with it...as close as possible.