Characters sit in an awkward semi-circle around a table so as to avoid anyone sitting with their backs to the camera/audience. This is a holdover from the days of theatre, when the audience's perspective was obviously fixed, and thus any actors sitting on that fourth side of the table would have violated two major rules of the stage: never show your back to the audience, and never block the audience's view. It was considered a classic Acceptable Break From Reality. One way to avoid this is via a Round Table Shot; but that tends to be used sparingly so it doesn't get annoying.