Yep, that one round was incredibly huge. It definitely surprised me (and the assignments took me ages), but it was wonderful. In general the exchange has always had at least 30 participants, usually between 35 and 40. And I doubt we'll get that many last minute sign-ups. It's mostly a pity because fewer participants make it harder to find a good fit for everyone, and of course the pinch-hitters will have less time to write something. Mostly I'm just baffled.