I think it's just that I was signed up to produce fic for Yuletide, then three different big bangs and the Not Prime Time all within seven months or so, and they were all single-fandom stories. It soaked up a lot of time and energy - I mean, my Yuletides added up to 12,500 words; then my 16,600 small fandom big bang; then 3,500 words for not prime time; my 106,135 extreme bigbang; and the pending het bigbang, which is 18,200 words. That .... adds up to about my usual total yearly output recently, lol. It didn't leave a lot of mental space leftover for the plotweaving that a good crossover requires.

Crossover shorts are still fun, though, never fear! I hope to have more coming up soon.