Murch stands when he edits.
One of the most important things he thinks every editor should do when chosing an out point for a shot, whatever their approach, is what he calls a 'flinch'. He rolls the shot and then hits the editing button when it feels instinctively right to turn away from that shot.
When he does this he logs the frame (or marks the neg with a grease pencil) where he stopped the clip, repeats the process and if he catches the same frame again he knows that was the right cut point. If he is out even by a couple of frames (there are 24 frames in a second of film), he knows that it wasn't quite right and he needs to look at that edit decision again.
"It's almost an involuntary flinch, an equivalent of the blink of the eye. That flinch point is where the shot will end," he says. "It's very similar to gunslinging. That's the reason I stand when I edit."
(quoted originally from a link now lost, itself citing The Conversations: Walter Murch and the Art of Editing Film)
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