Multi-Sub Publishers: Skip or Submit?

Occasionally, you will run into literary or genre markets that accept multiple submissions, where you can submit two, three, or more stories at the same time. These markets are pretty rare in my experience, much rarer than markets that accept simultaneous submissions. In general, they also tend to publish shorter works, either flash fiction or poetry, but there are a few that will take full-length short stories at two or three at a time.

So, providing you have enough stories sitting around, s...