When we worked for the State College system in Indiana in the 1980’s we used a computer system with the mainframe in Indianapolis and subsets at each of the 13 regional campus sites. Ours (near Louisville) was the only one on "Fast Time" (Eastern Daylight). That caused a real pain in the work schedule, when we went to work an hour before the folks in Indy (and the rest of the state) would start. Then in the evening , we shut down at 5 PM and they wanted info etc at the "end of their day"…we were long gone !!
Another quirk. When most people think of the time zones, they think in terms of the farther West you go the earlier it gets ( changing an hour at the time zone point each time). Well, When we would go North East towards Cincinnati We would cross from Fast Time to Slow Time at the county line, then drive 80 miles in Slow Time, until we got to the county line of Dearborn County (next to the Ohio Line) where we would switch BACK to Fast Time again. We could avoid the whole mess by crossing the Ohio River here at Louisville and driving in Kentucky to Cincinnati…being on FAST TIME (Eastern Daylight) the whole way.
Growing up as I did in SoCal where no one seems to pay any attention to the time changes very much, this area was a real mess in my mind for a long time. Luckily for the Arizona folks the population density near the state line is fairly sparse, so the impact of the change isn’t felt by too many, but here there are a lot of folks affected by the changes taking place now.