1. When a character is interacting with another character, and that second character leaves.
  2. And so the first character goes into a different room or closes a door.
  3. And then someone makes a noise in an adjoining room or knocks on the just-closed door.
  4. And the character assumes it's the person he or she had just been interacting with.
  5. The character may even resume the conversation that he or she had been having, before hearing the voice or seeing the face of the person they think has come back.
  6. If the scene is worth showing, it's not the familiar person. It's a function of the plot.
  7. (I'm watching the first season of Jessica Jones.)