Official Northleach Horror mugs (I’m in the middle) by art department Elias. Photo also by Elias.
You want to have a millisecond to pause just before shooting something, when you can think about if there’s some simple way to enhance it and bring it to life. Carol Reed paused before shooting the end shot of THE THIRD MAN, and as a result send two men up ladders with bags of dead leaves to sprinkle through the frame. That decision makes the shot. It often seems that you don’t have that millisecond to spare, but probably you do.
Always do a retake if you’re genuinely doubtful. Time spent filming is ultimately more valuable than time spent not filming, though of course set-up time is what makes everything else filming. But all that you’re left with afterwards is the precious seconds when the camera was rolling.
If you’re set up in such a way that you can see something you didn’t intend to shoot yet, shoot it. It’s free.
If what you are shooting makes no sense at all to an outsider, but perfect sense through the camera lens, then you are doing cinema, and you should continue.