I suppose it depends on how many meetings you have?

In our company's culture of few meetings, about 90% of the time I received a Slack message "Can we chat when you have a quick minute?" it was indeed the employee quitting. Eventually I would just respond in Slack to confirm they wanted to quit, so we could skip the dog & pony show that is assumed to be necessary for a "proper resignation," which I don't think employee nor manager enjoys.