Well, that’s not “the month” at all, though. At least not something I’d use outside of getting a rough idea for setting the next meeting, and absolutely wouldn’t use in code (but it’s probably fine for a todo - I’m complicating things, sorry ;-))

Edit: but perhaps that’s the custom used at many places and I’m just not aware.

A few people/companies I've worked with avoid using the last few days of the month for "monthly" things.

For example, "every month on the 15th", "every month on the 1st", etc. It makes it easier to figure out compared to "every 30 days" or "every month on the 30th, unless there are less than 30 days in the month"

That sounds reasonable. I'm writing a dumb, little journal/todo CLI tool for personal use ("meet with @farmer @Monday @13:30 regarding #carrots"), and the library I used for time has a duration for most things except month (i.e. you can't do 2024-03-20 + 1_MONTH), which makes sense.