I really came around to focusing on this with one middle school group I had where it took forever to fix anything, even though it was a very good group. I finally gave a little speak about how (and it was true) it seemed like each time we tried to fix something, for the first two or three times nothing got better. Then it was like they realized, "I guess he's not going to move on from this, so it must be important. We'd better focus or we'll be here all day." Once or twice more and it would be fixed. After that (and several reminders) it was much better, and I took the approach I described earlier. Instructions once. Get it right the first time.