For some reason at Sundance, more than other festivals that I'm aware of, you find filmmakers rushing to screen works that sometimes aren't completed. In my seven years of programming at Toronto, I'm not aware of any documentaries that went back for serious editing after their premiere - other than those presented as works-in-progress. But at Sundance every year there seems to be a few films that push the deadline so hard that they get taken back to the edit room afterwards.