The Do's and Don't's of Agreeable Conversation : Page 180
This does not mean, however, that one may not check anyone politely who is running on interminably or who is clearly in error on a significant point. An interruption that safeguards the point under discussion is not always reprehensible. If one says, "Pardon me, John, on that last point — it seems to me you might well add that the op ponents did the same thing" or words to that effect, it generally furthers rather than hinders the conversation.
But two types of interruptions are particularly annoying and indefensible. One type is frequent at parties composed of close friends or of married couples. One starts an episode, and the other falls in with, "No, that isn't the way it was, Jack. Don't you remember . . ." whereupon he says, "You better tell it." Not infrequently, when the second continues, the first will in turn interrupt. This sort of thing is done, not over significant points, but minor details. Any interruption to correct unimportant details in anyone's account is most objectionable. But especially husbands and wives and close friends should take a mutual