That's the same kind of mentality that kept Google Calendar from being able to schedule a monthly meeting on the last day of the month. If you scheduled it on t

That's the same kind of mentality that kept Google Calendar from being able to schedule a monthly meeting on the last day of the month. If you scheduled it on the 31st, the tool would happily accept that 5 months each year wouldn't have your monthly meeting. Suppose I have an 8am alarm to wake up in the morning. I want that to happen once per day in my current local timezone. If I change locations, the epoch I'm being alarmed at should change. If I travel quickly enough to experience multiple 8ams, I only want one of them (the first one). If laws change to give me multiple 8ams in a single locale, it's ambiguous which one I want. How your alarm app handles that varies, but you should do _something_ (flag the situation in the app, pick one (if one of them is about the same epoch as the previous alarm, maybe pick that one), ...). For calendars you have probably a different set of choices. If all participants are in the same time zone, you probably want the meeting to move as regulations change the definition of 8am. If they're in different time zones which all practice daylight savings and the meeting doesn't conflict with any of the 1-2am haunted hours then the meeting should probably move with daylight savings, reference the local time as it was defined when the meeting was created, and not move as some dictator redefines a time zone (becoming a cross between a display issue and actually considering local time). If you don't know anything as a calendar app about the participants, there will be edge cases where you make bad decisions, so you either accept that or flag the ambiguity when appropriate. And so on. If we can convince everyone to switch to some kind of atomic time without leap seconds I'd be tickled pink. That's not the world we live in though.