// call foo() one day from now:
    sleep(86400); foo();

our personal convictions don't change that fact.

You could assume that a day isn't exactly 24 hours, but it's close-ish to 24 hours. Nope, not even close.

And that assumes that we can treat an hour as a precise measure of time (we can't). On some systems, even a second is not a precise measure of time (second smearing).

To make things worse, those are "simple" edge cases.

Time is hard. I'm not sure if I can make any statement about time that is true.

There’s no single time unit that works for all situations.

Some countries start on a Friday or Saturday and until 2022 Iran could start any day of the week although never at 3AM.

Ramadan is observed from one visual sighting of a crescent moon to the next.

Cloud conditions may prevent sighting and thereby alter the official start of Ramadan for an individual location, and from time-to-time, the start of a country's change in timezone.

Only Morocco does this, I believe, and it's not even clear that that's actually official time at this point. In 2018, Morocco abolished DST, but it seems unclear what that means in practice.

I'd love it if someone from Morocco could weigh in on what the actual situation is on the ground. Do people still change their clocks for Ramadan? Would they be annoyed if a website kept Moroccan users on standard time during Ramadan?