I print to (from RVP trannnies) 81x61cm from 6x7 (do the math in inches...). At this moment an 12x18 print is coming off 35mm. I don't shuffle prints into a folder never to be seen again: they are framed and put under spots.

Print size should be accorded consideration as to its final use. Where are you putting them? In an archival folder as part of a "reference library", or framing?
Economies of scale will dictate print size to a point. No doubt whole books have been written on what print sizes should be produced, why and what for. Print to a size you want and need, which fits the bill for the end result. My next target is to print about 900cm tall (hybrid process): wallpaper for a stair landing.