alt Hacker NewsAs a consumer I used to use it all the time, though it matters a lot less these days. Two A4 pages at 50% zoom (A5) fit on one A4. You could cut your printing cost for drafts in half by doing that, back when we had to actually print to check the layout. Same went for posters etc, and since the aspect ratio was preserved it was really handy to preview at home on A4 sheet before taking it to the print shop.
I’m sure you can do that on other size systems, but ISO paper sizing gives you accurate scaling.
Same goes for photocopies, photocopiers can scale copies so two A4 sheets copy to one, if you don’t need the same size.
> Two A4 pages at 50% zoom (A5) fit on one A4.
This assumes there are no errors anywhere in the sizes or alignments of the A4 base page or either A5. Otherwise, you'll have an A5 running over an edge of the A4 or both A5s overlapping in the middle.
If your pages are designed with margins on the assumption that errors in the paper are common, this issue disappears because the margins cover for it. But still, if I wanted to do a display of two 8.5" x 11" sheets of paper, I'd want a board that was bigger than 17" x 11".