There's an act you may have seen, where someone balances a lot of spinning plates on top of poles. They'll stay there as long as they're spinning, so he has to run back and forth tapping each one as it slows so it doesn't fall.
That's me. (Or that's what it feels like.)
I have twelve publishable short stories at this point, and eight of them are spinning right now, meaning they're out there pending rejection. (Or maybe acceptance. You never know.) But every time one is rejected, I have to send it out somewhere else right away, and that's a lot like the guy with the plates.
But...that's MUCH easier than it was at first, sending out multiple submissions a day. Each magazine's requirements are just different enough that doing a lot of them at once feels like filling out income tax forms.
Image credit: Henrik Bothe, used under Creative Commons License 4.0