There are many ways of doing band pull-aparts. When I use them as extra work between sets I don't count reps or time – the goal is simply to put the muscles under tension, not to do a specific number of sets and reps.
With the therapeutic variation, once tension is established simply do slow movements until you find a sore or weak spot. When you do, spend some time keeping that spot under tension until the pain/soreness decreases.
related posts
Exercise Progressions for Bigger Pulls
Slow down there, Hoss; you can't start pulling heavy weights from the get-go. Let us show you the proper progressions to make your deadlift truly worthwhile.
Training Disasters
Tony shoots apart training myths like they were ducks and he was a starving fat man sitting in a pond with a rifle. Read about the "other side of the core," deadlifting mistakes, and the pencil test. (You gotta' take the pencil test.)
10 Forgotten Tips for Smarter Lifting
Mike Robertson wants to remind you to do some of the great stuff you used to, but may have forgotten about.
Tip: The Banded Shoulder Press
Have a hard time building delts? Try this simple yet effective shoulder press using a band for accommodating resistance.