3 or more aircraft in the circuit, Andrew? Sounds scary.
The busiest non-controlled aerodrome I've been to in Australia is Temora on Warbirds Downunda days - the slot for arrivals before the Romeo gets a bit busy, and the stampede of departures when the Romeo ends is very entertaining.
The Bicentennial Air Race was also fun, with departures every 30 seconds and lots of aircraft with approximately the same performance converging on the same spot at the other end.
Not enough enough fingers to count the aircraft on finals, base, downwind and reported inbound. Nobody's doing 2,000' overflies or fretting about high performance aircraft or overhead departures.
When you mix it in higher traffic densities in the circuit, seeing other aircraft in close proximity is not such a big deal. It's just Bankstown or Jandakot in their heyday, without ATC.
What's "extreme" seems to be something in the eye of the beholder. If someone chooses to stay away from the circuit while someone else departs, I'd call that "their decision" with no greater safety risk than going through the joining procedure while the other aircraft is lining up and departing.