There’s also the issue of week-of-year calendars being useful for a very small niche, so it’s basically technical jargon of one speciality imposed on the rest o

There’s also the issue of week-of-year calendars being useful for a very small niche, so it’s basically technical jargon of one speciality imposed on the rest of the world, the same way lawyers debate commas and treat and & or completely differently to sane people. Familiarity with strftime is part of gaining experience in the field, and will usually involve using YYYY until it breaks and then finding articles like this one written over the last two decades explaining that you have tripped over a loose paver that everyone else in the industry already knows about (but at least now you understand why there are so many broken wrists). There’s a similar problem in orbital mechanics where people try doing a calculation using Kepler’s equations, but because they’re using degrees they get the wrong result. Of course the equation is entirely in radians, which they quickly learn about but not before suggesting that the languages or APIs they are using need new features to help other people avoid falling into that trap.