Hmmm... I'm not sure that's true. Looking around my desk (in London, UK) I have - a few flyers (A5) - much more convenient for people to hand me in the street

Hmmm... I'm not sure that's true. Looking around my desk (in London, UK) I have - a few flyers (A5) - much more convenient for people to hand me in the street, big enough to get information across on, not to big to big cumbersome for me and (presumably) cheaper than A4 to print in bulk - a postcard (A6) from a colleague who went on a lengthy vacation - business cards - some (but admittedly not all) of which are A8 - and lots of A4 - it's what I print out when I need a hardcopy. I don't currently have any A3 on my desk, but I've used it in the past when I have complicated diagrams to analyze and want to get it all on one sheet. I often print out documents as 2 (or sometimes even 4) pages to one A4 sheet to make it easier (and more tree-friendly) to read away from my computer - this works OK because the aspect ratio remains the same.