I recommend that short story authors write according to the editor's requirements after they have researched the markets. But some writers want to be able to maximise their chances by targeting a few publications in the same market.
However, whilst some magazines within the same market are looking for the same kind of stories and similar subject matters (especially with twist stories, relationship stories, and mystery stories), every editor is likely to have slightly different (and perhaps incompatible) requirements. The differences between editorial requirements can often be minor - it may boil down to a different word count or point of view.
When I set out to write a story, I tend to have one particular magazine in mind. I call this magazine my 'first choice' for that story. I write something that suits the length and requirements of the magazine and send it off to the fiction editor. If it's accepted – great! If the story is rejected, all is not lost because I can then rework/rewrite it to fit another magazine that publishes the same kind of stories. This may involve editing/adjusting the story to shorten or lengthen the word count, or changing it from a first person to a third person point of view, or even changing the ending to make it more 'up beat'. In other words, making sure the story matches the requirements of my 'second choice' editor.
You may decide you want to write more generally to create a story that fits well into the requirements of two or three similar magazines. It's OK to do this but, if you do, I wouldn't recommend that you submit the same story to all of them at the same time (called a simultaneous submission). In theory, you could do this and wait for your first acceptance to arrive. You'd then have to quickly let the other editors know that the story is no longer available. However, it would be tricky if you got two acceptances for the same story at the same time. You'd then be in the difficult position of having to tell one of the editors that you've sold the story elsewhere. I've never done this myself, but I've spoken to a few fiction editors over the years who've all said that they aren't happy when this happens (it really seems to annoy them). In the great scheme of things, I suppose it's not an earth shattering problem, but if you hope to work with that same editor on a regular basis, you're better off steering clear of simultaneous submissions. By submitting a story to one editor at a time, you will avoid any conflicts or dilemmas and hopefully be able to build successful relationships that will allow you to sell regularly to a range of magazines.