My favourite model of 'when to interrupt' is two approaches to interruption: Those who expect an interruption once understanding has been reached, and those wh

My favourite model of 'when to interrupt' is two approaches to interruption: Those who expect an interruption once understanding has been reached, and those who expect complete statements before interruption. The failure modes from when these two different approaches mix is either "awkward" or "rude". Generally, if someone is rambling, interrupt them. (With exceptions like if someone is emotionally venting, let them release it).