Metal roofing thing (idk how to translate, am not british) are always in mm. We would buy them at like 5 meters long and measure for cutting using mm. https://limarija-sebastijan.hr/krovni-zidni-i-ostali-profilirani-limovi/trapezni-lim/ All the drawings for metal things are in mm. What is not is like diameter of the pipes. The store I linked sells rolls of sheet metal (again don't know how to translate) in cm, but all the other stores sell in mm. https://olx.ba/artikal/19038696/lim-u-rolni/ When you want custom bent stuff (like the metal.. things that go on the sides, or custom gutters) you make a drawing in mm (can't explain, but I'l draw one if you want).
I just said "professional" because the one I replied said it, without saying what profession. Roofing is a profession, and metal roofing stuff doing (again don't know how to translate) is also a profession.
And all the schematics I have seen for metal parts, and in cad software in general, is in mm. Tailoring is also in mm (https://tehnicki.lzmk.hr/clanak/kroj).
Maybe it is a US vs rest of the world thing ? Maybe I'm not expirienced enough to make such sweeping statements.
Again, you put thousands of mm because mixing cm and mm (and m) can lead to mistakes. I even remember cutting wrong because I heard like 2570 instead of 2507 (he's up there measuring, while I'm down cutting).
House blueprints are usually in meters. Window sizes are in cm.
Sure. I'm not a professional machinist. I have worked on roofs and all sheet metal things are in mm. I have even worked for a company that makes those metal things and as a customer for another one. I also was by far the best at technical drawing in school, not to brag. And all the schematics for things I have seen are in mm, for example https://www.iclarified.com/images/news/48931/228250/228250-1280.png . Disclaimer, all the schematics that are not in, ugh, inches (or architecture).
Sure, if I made something for someone they can give me dimensions in Smoots for all I care. But I would transform it into mm, and would never buy tools that don't use mm.
For context, I am not in an english speaking country nor Myanmar.
Edit: Actually I have seen house schematics in mm as well. I thing they now give out in m, but use mm internally (depending on architecture firm).