It’s quite different from how I think about time, as a programmer. I treat human time and timezones as approximate. Fortunately I’ve been spared from working on calendar/scheduling for humans, which sounds awful for all the reasons mentioned.

Instead I mostly use time for durations and for happens-before relationships. I still use Unix flavor timestamps, but if I can I ensure monotonicity (in case of backward jumps) and never trust timestamps from untrusted sources (usually: another node on the network). It often makes more sense to record the time a message was received than trusting the sender.

That said, I am fortunate to not have to deal with complicated happens-before relationships in distributed computing. I recall reading the Spanner paper for the first time and being amazed how they handled time windows.