My method is fairly simple. You only need a wipe off board and the time it takes to have a classroom discussion. Posting a board next to the door allows students to leave without disrupting the flow of the lesson and also allows you to know where everyone is at all times. If it is ever an issue of "over-use" the students simply talk through the concern and take actions to remedy their behavior. They know before it is mentioned that they should be responsible and respectful. This promotes both of those things.