I have a bad habit of talking over people. I first noticed it at my last job, and my boss even called me on it once. At my new job, I catch myself talking over people who I am talking to on the phone. I think there are positives and negatives.
Obviously, it is rather rude to talk while someone else is talking. I tell C this almost every day. It is disrespectful, and sends the message that what the other person is saying is not as important as what I have to say. I'm working on it, I really am!
However.... I think it allows me to control phone calls at work. I don't know if you have ever worked in a call center environment, but people like to talk. And I think they often, probably unconsciously, feel they have a captive audience in a customer service rep on the phone. This is someone who can't be rude, and can't hang up on them. So, sometimes, gently talking over them can sort of steer the conversation back to the business at hand. I think I just need to work on the gentle thing.