Other countries have made these changes on shorter time frames in recent memory. I don't recall hearing about any catastrophes.
In 2011, Samoa changed time zones to land on the other side of the international date line. I don't believe that was years in the making. Even last year, they announced they would no longer observe daylight saving time; they decided that 11 days before they were scheduled to switch their clocks.
In January of 2015, Chile announced they would keep daylight saving time year-round when they rolled forward in April. Then in 2016, they scrapped that. In 2019, they even changed the dates on which daylight saving started and ended. While this was over the course of several years, they didn't go into this thinking about how to make it complicated for the next four years.
Many of the states don't seem to think this is a serious concern, either. Several, including my own (Kentucky) passed legislation to permanently observe daylight saving as soon as Congress would allow it. I don't think the folks considering these measures are underestimating our ability to deal with these types of changes.
The late changes to daylight saving time rules pretty much always mean that for several days to potentially over a month, users will be encountering systems with the incorrect time. Often times they will try to "correct it" by manually changing the system time but then time sync services might undo that, and if not, then once the time zone package finally makes it to the system, it "breaks" again, because the user should not have messed with the clocks in the first place.
The authors of the time zone database strongly encourage long notice periods for changes, as there are plenty of programs that use this data that have a month or more of delay between when an updated database is published, and when end devices will realistically get the update. And that is for people who don't habitually put off updates!
When DST rules were last change we had about a year and a half notice, which is realistically what this bill also provides.
In 2011, Samoa changed time zones to land on the other side of the international date line. I don't believe that was years in the making. Even last year, they announced they would no longer observe daylight saving time; they decided that 11 days before they were scheduled to switch their clocks.
In January of 2015, Chile announced they would keep daylight saving time year-round when they rolled forward in April. Then in 2016, they scrapped that. In 2019, they even changed the dates on which daylight saving started and ended. While this was over the course of several years, they didn't go into this thinking about how to make it complicated for the next four years.
Many of the states don't seem to think this is a serious concern, either. Several, including my own (Kentucky) passed legislation to permanently observe daylight saving as soon as Congress would allow it. I don't think the folks considering these measures are underestimating our ability to deal with these types of changes.