Well, my RL group moves at a snail's pace generally, so I was surprised when we got to this last encounter so quickly. At that rate we're going though, I genuinely think it'll be about a year to get to this next one I have planned - it's the finale for this campaign, and it's been 3 years in coming.
If there genuinely is nothing else, I could potentially bring in the elements I had planned. It would probably be quicker than this one - more straightforward but with a difficult setting and opponents. Smaller arena, too.