Movie dialogue is supposed to APPEAR TO SOUND like real-life conversation without actually BEING like real-life conversation.
Most of what people have to say in a particular real conversation is not that interesting to other people, only certain elements are. If any.
All of the dialogue in a film or TV show is supposed to move the story forward, so limit it to the meat of what you want to impart to the audience. Make it sound they way people talk in real life but without all the usual fluff, extraneous information and tangents.
Think of dialogue as Talk Light, only with much more meaning and drama. Or humor.
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