Israel used to have the switch data determined by a parliamentary vote, and changed almost every year. Depending on the political power distribution, the date w

Israel used to have the switch data determined by a parliamentary vote, and changed almost every year. Depending on the political power distribution, the date was moved back and forth. I don't remember the exact details already, but it was related to Jewish holidays, which involved morning prayers, so sometimes it was more convenient for certain people to move the time scale back or forward, and since Jewish holidays are celebrated following Jewish calendar, which moves around relatively to Western calendar, and since sometimes religious parties had enough power to get special consideration and sometimes they didn't... You can look at the result e.g. here: https://git.launchpad.net/pytz/tree/tz/asia https://git.launchpad.net/pytz/tree/tz/asia (look for "Zion" there). They thankfully finally stopped doing it in 2013 and arrived at a stable rule, but until then you can image how much confusion it caused.