Telling the story through action. #BusterKeaton was a visual story-teller and he avoided title cards (aka #intertitles): "The average picture used 240 titles. The most I ever used was 56. We eliminated #subtitles if we could possibly tell it in action."
https://youtu.be/UWEjxkkB8Xs?t=75

Old-school #subtitling used the same logic. If the message is obvious from image or sound, no need for a subtitle. E.g: "Hey" is often used in films when a character wants to get another's attention. This used to be omitted in the subtitles, esp. if gesture/movement is visible

New norms seem to dictate a need for a subtitle each time a sound comes out of a mouth, even if almost non-verbal (e.g. a screaming "Nooooo" which could also be just a scream).
#subtitleomission #redundancy #recoverability #complementarity