As a young engineer right out of university back in 1985, one of my early tasks involved merging together a bunch of telemetry data provided on mag tapes recorded at different radar sites (in the USA). One or two of the systems time stamped their data in local time, and all the others used UTC. I remember buying one of those old Farmers' Almanacs in order to make an algorithm to account for DST. When I read the rules, I threw up my arms in despair.

The almanac gave nominal rules for the transitions. But there was a footnote explaining that these transitions had and will continue to be adjusted year to year due to Congressional intervention. I showed this to my boss and said, "If I could write an algorithm that predicted future votes of Congress, I would be a billionaire and could quit this engineering job."

I think in the end I coded the algorithm with the recent known transitions, and the nominal rules for future ones. What else could you do (this was before everyone was networked, and the code ran on standalone computers like a VAX).

I also learned that task of merging three sources of tracking data, each with its own validity and measurement degradation status, was an absolute nightmare. But still easier than predicting future actions of Congress.