Back in the day, the rule was that if you took the second to last cup, you called out “last cup”. Someone would call out that they would take the last cup, or it would go down the drain.
At that time, depending on the time of day, you made another pot, or cleaned up the mess for morning.
Clean up time was, say, after 1100 or so.
The only time I ever dealt with this, the company had one of those dual-pot coffee makers so there was one for decaf and one for regular. The etiquette there was to make coffee in 8-cup batches using carafes that could hold 12 cups. Someone had a measuring spoon where one spoonful of grounds gave you 4 cups of coffee, and they had a container marked off in 4-cup increments.
So, first thing in the morning, someone started it all off with 12-cup batch. For everyone else, you started a new 8-cup brew cycle anytime it got below about 3 cups. Or if enough people were there to simultaneously finish it off, they did another 12-cup batch.
This was a campus bookstore that open 14 hours a day for parts of the year, so this pretty much went on all day. Some coffee went stale in the afternoon, but we had plenty of people drinking it in the evenings. (The irony of this bookstore: the break room was the only “department” that was managed well.)