This is a weirdly long thread, mostly unrelated to NANOG, it seems. The work for how this will be implemented in most of our computers happens on the TZ list by thoughtful people with lots and lots of experience on the subject: https://mm.icann.org/pipermail/tz/
I believe the last change in the US was more than a decade ago, but time zone data changes somewhere in the world on a very very regular basis. Ask
