This concept, BTW, isn’t completely alien to European media. In the German state of North Rhine-Westphalia for instance, Radio NRW provides programming for 45 local stations that also produce their own (local) content. This is radio, though, not TV.
This. I’ve learned to skip articles in newspapers and magazines about a new show that’s coming to PBS, new series of Mystery, etc. because my local PBS station never shows them anywhere near the supposed premier date. So, by any normal definition, PBS is not a network.
I’m not sure that the OP’s question about time zones has been answered completely.
Networks send programs to affiliates in two batches. The first one goes to the Eastern and Central time zones. Given that 8:00 EST is 7:00 CST, prime time in New York or Boston or Savannah runs from 8:00 to 11:00 P.M., which is 7:00 to 10:00 P.M. in Chicago and Omaha and Gulfport.
The exact same three-hour block of programming is sent out a second time from 8:00–11:00 P.M. Pacific time, which is, I guess, 9:00–midnight Mountain time.
Is that right? Do people in Salt Lake City watch their local news at midnight?
The Mountain issue has always confused me but I think it works like this:
Feed 1 goes out at 8 pm Eastern and is shown live in Eastern (8 pm) and Central (7 pm).
At 9 pm Eastern, a recording of Feed 1 is shown in Mountain (7 pm).
Feed 2 goes out at 11 pm Eastern and is shown live in Pacific (8 pm).
In Salt Lake City, Denver and Colorado Springs, prime time is 7-10 p.m.
But in Phoenix, El Paso and Albuquerque it’s 8-11 p.m.