Curiosity got the better of me, so I went and took the trouble to plot stories against first submission date. I haven't been recording the actual date written, so this is the closest thing I have. Several of the pre-bootcamp stories sat on my hard drive for several months before I submitted them, all of those were flash.
I still don't see any real pattern, maybe because I write the story in my head first, and it just is as long as it is. I'm not sure what all this proves, but here it is.