Perhaps random was the wrong choice of words. The construction of the theoretical time zones is completely non-random. Some of the country specific changes seem to be though.

I was thinking of the time zone carveouts that wrap around some islands - like Kiribati, where the IDL swings around it with giant straight lines that don’t resemble it’s EEZ. How were they decided? I can’t seem to find anything on it.

Seems though, for most international ocean travel, it doesn’t matter (per your excellent links- thankyou). Ships just use an idealized date line at 180 until they hit an EEZ and will use that if they need to communicate with that country.

Really interesting!
I did a bit more searching and found This article, where the author intentionally used EEZ boundaries to make a time zone map that incorporates sovereignty.
He stated that currently Maritime time zones are randomly drawn straight lines on a map, that aren’t representative of the country that’s forcing change.

Ok so this raises a question that I couldn’t answer satisfactorily myself by googling.
Are deviations to time zones a land thing?

What I mean is that the Northern Territory in Australia follows UTC +9.5, despite being in what would be considered the +9 band.
OP’s map shows the NT border, but the wiki image on time zones shows the boundary of the time zone extending into the sea between it and Indonesia.

Does the time zone change (between +9 and +9.5) when I step foot in the NT, or does it follow something like the Exclusive Economic Zone?

Could be Falkland islands? They’re 3 hours behind UTC, but that time zone band it’s in would be for -4 Amazon time

Yeah but none of our coast is the edge of a time zone (unless it showed daylight saving), so we’re invisible. Kind of cool.

Everyday, big thing in schools.

Touch screens?