At WVROX, we played just about every single iteration of the 24 teams on the field. Granted, running 24 hours will do that for you.
We had a long cycle time, but still ran so that every team played against and with every team, multiple times.
As far as my experience, at most events, you will not see repeats. I think the only repeats we have seen on our team that I can think of were due to surrogate matches. At most events, we don't even get to see every team on the field (whether for or against), so we actually see no repeats.