I'm one of the ones who didn't post nearly as much as I expected. I think my list made it a bit challenging - most of the crossovers required a lot of thought to figure out how to get them together. But for me it was mostly that I wound up distracted.
I ended up writing three of the prompts, and there were five more I intended to write, but four of them ended up getting turned into an original novel instead o.o;;; The fifth was the 'fighting crime' one, and while I had a grand time planning the universe, when it came to the actual story I never really got inspired too much. Not really sure why.
I'm curious to hear what the statistics were. For me, I found the ones were you only specified the title were the hardest to come up with an idea, especially since I'm sure the titles were meant to have some kind of significance, and they completely escaped me.
This was a really fantastic challenge and I would love to do something like it again! I could probably content myself for a very long time just doing something like this, trying out different character lists and different prompt lists.