Re: What's too many regarding multicrosses?
...But less challenging. 
Of course, I'm saying that when I have a story that I'll have finished soon (hopefully not too much later than soon) that might just be one of the best handling of time travel in Sailor Moon since ever. And that's coming from a person who is normally self-deprecating. @_@
To get more on topic, if it's a serious story then I think the limit regarding the amount of series being crossed over with would be defined by how many of said series' settings and mechanics don't come into conflict with any among themselves. Unless you're fusing the series together, of course: in which case that's another matter entirely.
Of course, I'm saying that when I have a story that I'll have finished soon (hopefully not too much later than soon) that might just be one of the best handling of time travel in Sailor Moon since ever. And that's coming from a person who is normally self-deprecating. @_@
To get more on topic, if it's a serious story then I think the limit regarding the amount of series being crossed over with would be defined by how many of said series' settings and mechanics don't come into conflict with any among themselves. Unless you're fusing the series together, of course: in which case that's another matter entirely.