Comment by thaumasiotes
2 days ago
> 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".
Sizing errors are essentially unheard of, and I've never seen anyone having any trouble with joining or folding ISO paper to go one size up/down. It's a completely normal operation, which people working in printing and publishing will routinely do without a second thought.
For commercial printing, there's the SRA paper series (Supplementary Raw) which is designed to accommodate bleed and alignment bars. An A4 glossy magazine, for example, might be printed on SRA3 and will be trimmed, folded, and stapled automatically at the end of the printing process. But that's a technical detail for the printer to care about - the publisher or designer might specify "folded A3 with bleeds", and the printer will choose the correct raw format to provide that within their printing system.
As the other commenter said, alignment issues have never been a problem.
If you're manually aligning the sheets on the photocopier bed maybe, but the edges are set up for that so it's never been an issue for me. However every photocopier I've used that was made since the late 90s lets you do the sheets individually so you can use the copier bed to align each one.
Because the ability to scale like this is so ubiquitous we're just all used to doing it.