In Fenimore Cooper’s Literary Offenses, he lists as #5:

“…require that when the personages of a tale deal in conversation, the talk shall sound like human talk, and be talk such as human beings would be likely to talk in the given circumstances, and have a discoverable meaning, also a discoverable purpose, and a show of relevancy, and remain in the neighborhood of the subject at hand, and be interesting to the reader, and help out the tale, and stop when the people cannot think of anything more to say.”

During the reading of this rule my mind went directly to Attack of the Clones.