Alt text: They're up there with coral islands, lightning, and caterpillars turning into butterflies.
plus 5 days every year that's not part of any month?
Just add a leap month every six years
You'd have 12 30-day months most years, and an extra in the sixth! While we're at it, we can redefine a week to be six days, so there's a perfectly rounded number of weeks per month/year! Days, hours, minutes and seconds are already fine, but maybe we should also replace units shorter than a second with something more dozenal/hexal(?), too…