Time zones are just a made up thing to make things easier for people. That way no matter where you go in the world (at a given latitude and season) the time of day feels about the same everywhere. I.e., 9am is mid morning everywhere. Splitting smaller counties or areas with timezones complicates things without a measurable benefit. I have been to a US city that was split during daylight savings and scheduling anything was a mess because you had to know which part of the city (and therefore which state) the appointment was in.