I honestly don't know what printing techniques they're using, but even with a digital sheet fed press they would still want to simplify collating as much as possible, right? Repaginating a odd number of cards onto a looping print run sounds like a nightmare unless it could be done automatically or on a web fed press or something, and even then, sorting them could be a disaster.
I mean, does 10,000 copies sound about right for a print run of an expansion? More? They couldn't possibly do that by hand cheaply, even if they outsourced it to Mexico, could they?
I know that WotC (Magic the Gathering) used to get their printing done by Cartamundi and they had a rare sheet, an uncommon sheet, and a common sheet. Commons, at least, would be sorted into packs not completely randomly, but in pairs, so that any common was very likely to appear in a pack with either the common before it on the sheet, or the common after. This became such a part of high level tournament drafting that it was preserved when Wizards started selling digital packs for online play.
But the upshot of this was the same there as here, once the sheet is full, you cant print only one more card, you gotta print a multiple.
