reminds me of this list of falsehoods programmers tend to think
...
◦ The offsets between two time zones will remain constant.
◦ Daylight saving time happens at the same time every year.
◦ Daylight saving time happens at the same time in every time zone.
◦ Daylight saving time always adjusts by an hour.
...
https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca