^^Yeah Marc, fat lot of good it does since they have (or at least had) a habit of stacking all the trains at once.
Same for Dueling Dragons.
And I thought Screamin' ran at least five trains? RCDB says six, but I don't know if they run them all at once...
And don't forget Air usually runs three!
Off the top of my head, I've also seen Khan, Medusa, Nitro, Behemoth, Apollo's Chariot, Alpengeist, Kumba, Montu and Kraken running three. It's more a case of parks only running three when it's busy enough to warrant it, and two/one when it isn't.