Submitting multiple papers to the same journal simultaneously I know that it is ill advised to submit a single paper to multiple journals at once. But what about multiple papers to a single journal? For instance, I have a few different drafts that I could clean up, which would probably fit well in Mathematics Magazine. I don't know how long it takes for a submission to be accepted or rejected. Is it acceptable to submit additional papers before hearing back about the first one?
I don't see any downside to this as long as the ideas in the papers don't "compete" with each other. But if they are sufficiently different it should be acceptable. 

That would not be the case for Special Issues, where the editors will be looking for a variety of authors/viewpoints/... but for ordinary issues it should be fine. 

However, unless you are a recognized superstar in your field, don't expect more than one paper to appear in any given issue. It might be useful to you, if you are a bit new at this, to try out your best paper first and see what reception you get. If you get a good response you could try to be more bold in the future.