I am pretty sure I have never before had 43 submissions out at one time before. But it is actually not very hard to do.
Once in a long while, I write a story that does not have any wizards, or clones, or spaceships in it. In fact, it does not have any magic in it at all. Normally, when I write a story with even the vaguest hint of magic or SF-type stuff in it, I submit it to genre markets, because that is what I am familiar with. However, sometimes that just cannot be done. Genre markets are kind of snobby actually, and refuse to look outside their comfort zone and take a chance on non-genre work.
Thus, if I want to submit these works, I am forced to venture into the weird, marginal world of literary magazines. That is why I put my non-genre stories on a distant shelf for over a year. Even when I began my revision quest (I have revised 17 stories so far, this year…wooo!!) I left the non-genre ones for the end.
But…I finally got to them. And that’s when I remembered the bestest part about the non-genre literary world. For some reason, most of their magazines allow simultaneous submission. So I sent one story — the best one — to the eight or nine literary magazines I’d actually heard of. And I sent the rest to all the other magazines (as long as they have acceptance rates below 1%, as reported on Duotrope…I do have some standards). That is how I have 20+ stories out at 40+ markets. I am so going to get to my 700th rejection within a month or two.