Play is cut into scenes. A scene opens on a place and a question — will she tell him, does the door open, is the debt called in — and it closes the moment the question has an answer, whether or not anyone is finished talking.
Opening
Whoever frames the scene says where it is and who is present. They do not say what happens; that is the table's job.
Closing
Cut early. A scene that runs past its answer is where a session loses its shape, and there is no rule that can rescue it — only the habit of cutting.