An alternate calendar system briefly used by republican France. It had 360 days per year with 5 or 6 “intercalary” or leap days between years. It had 12 months of 30 days, which were comprised by 3 weeks of 10 days. Every day of the year had a unique name: a common plant, animal, mineral, or tool/equipment (ie January 31 was “Broccoli” and May 4 was “Silkworm”).
YSK because it’s an interesting alternative to the Gregorian calendar and the occasionally-proposed 13 month calendar.
Though it did have some problems such as starting in late September (very unusual for a calendar) and not having a robust leap-year system.
Starting the year in January sucks. Ancient civilizations had it right with a start of the year at the Spring equinox. The original design by Sylvain Marechal, right before the Revolution started, did start in March…
That’s completely irrelevant to my point, which was that in a calendar of 12 30-day months you can’t have a 31st day of any month.