I work in Europe and have colleagues in the east coast of the US. The dst switches happen a few weeks apart so twice a year everyone gets fucked up schedules for two weeks because meetings move with the time zone of the person who created them. We have specialised tooling to notice if computer programs will behave weirdly because a job is scheduled to run during the hour of the night that happens twice/not at all (obviously one solution is to avoid scheduling jobs in local time but if you need to react with the real world where things are scheduled in local time, this becomes harder).