A common example is faculty meetings, when Distinguished Professors A, B and Q are free to butt in when they have an idea. Whether or not this works depends on the extent to which Irrelevant Professor F or Invisible Grad Student P take umbrage at being interrupted. There are other examples where a lecture is entitled "Conversation on X", but in fact it is primarily a monologue by a single speaker, with allowances for question and answer at the end.
Traditionally, a "conversation" has a small set of individuals who take discrete turns speaking for a short period of time (maybe a couple of minutes at most) on a topic. By definition, a conversation is turn-taking between equals. We have other words to describe utterance-exchanges that don't follow that form (e.g. lecture, "class"). A "discussion" is a notch up from "conversation", so that one can hold forth for much longer in a "discussion", and a discussion is usually organized around a weightier proposition.