36 day month is just as arbitrary to me as having 28-31 days per month though, and do you make a week 6 days to fit the length of a month, or keep it at 7 since it doesn’t really evenly divide into current months(aside from February 3/4 years), anyway and then those extra 5-6 still messes up the rotation. National holiday sounds good if you’re doing the kind of work that can be put off for the week, but becomes a pain for business that need to keep running through holidays, particularly a holiday that lasts more than 2 days. Lots of our economy is based on things like standard work weeks/months, billing on monthly basis, etc.. At best I think we could shuffle a couple days from the 31 day months to February so it’s more consistent, or make them all 30 and make things like solstices/equinoxes/new years day be the extra 5 tacked on to (or between, but consider it part of the month for purposes like monthly billing) the appropriate months. Lots of disruption for minimal gains though.

Really, we have the second defined well in SI, and there’s no real reason we couldn’t just use that with the usual prefixes for things that don’t need to correlate with the calendar. When we get to the point of colonizing other worlds then there’s an argument to make some consistent standard to accommodate each world having a different solar day/year but as long as pretty much everybody hangs out on Earth I just don’t see any significant benefit to trying to metricize timekeeping.