I've never edited something where mistakes haven't been invaluable. You have the perfect shots and the smooth transitions, but it's what you didn't mean to film that becomes vital. A few seconds of somebody after the take has finished, smiling or laughing at something unrelated, or not paying attention at all. These bits can save a scene. Sometimes a shot becomes boring and you haven't got anything to cut to. That's when I look around the edges of takes, when people are just waiting for things to happen. Cut to that. Looks intended. Done. For how to be god, even the bits where they look at the camera are useful. So I try to keep the camera on for a while longer than I need to. Accidents don't happen by themselves.
It's all going fine. Episode two will be made obscenely soon after the first one. And episode three will be made after that. And then, if I'm very lucky, episode four.