Last year I flew out to Denver to watch clients Big Head Todd and the Monsters perform at Red Rocks Amphitheater. During sound check they were rehearsing Led Zeppelin's “Misty Mountain Hop”, which they were going to open the show with. For some reason they just couldn't get the beginning of the song to work. Things were not quite syncing up right between the four of them.
What was interesting is that they didn't keep at it. After going through it several times, they just said never mind and called sound check done.
Later that night when they kicked off the show, they nailed it. Not an issue. Afterward I asked Todd about that. He said sometimes you just get stuck in a bad cycle and the best thing you can do is step away from it for a bit. - Cris