I've seen small gaps between pieces in some cases, specially in those who are in very complicated angles.
If they are just a few and small (ie, 2 or 3 gaps of 1 mm) I don't think it could be a big problem, however, a lot of small gaps or a couple of big gaps can ruin the whole model sooner or later.
If by "gap" we mean edges that aren't lined up properly: That shouldn't happen at all. If you make the same mistake on both sides and/or are lucky, then maybe it doesn't matter. But usually this leads to some kind of warpage.
I tried a height of 11.5 inches, but that was far too small. I think it was roughly 16 pages. So today I bumped it up to 14 inches, but that ended up being 42 pages with over 1000 faces to it.
Does it have 42 pages before or after rearranging the pieces?