Before the development of videotape in the late 1950s, networks had to run filmed programs or telecast them live across the four continental time zones simultaneously. In the beginning days, the entire daytime schedules were telecast live on the Pacific and Mountain time zones, with prime time programming using film to run the shows in the desired time slots. Film was expensive to develop and edit, and to send them out to TV affiliates were costly. Some of the shows were shown live from coast to coast.
When videotape was invented, it provided a quick and cost-effecient way of distributing programming that was designed to be recorded earlier from the East/Central feed for re-broadcast later in the Mountain and Pacific time zones to the west. In lieu of using videotape, some Western affiliates aired a network program from a neighboring like affiliate by aiming an antenna towards the distant TV station, importing it into the station and rebroadcasting the signal locally. The ABC, CBS and NBC TV stations in Los Angeles were the defacto originators of the Pacific time zone feed for years until the networks originating from New York finally established feeds for that time zone; from researching the 1950s TV Guides from Seattle, Washington, which sits in the Pacific Time Zone, the daytime lineups were run live off the East/Central feed, instead of from a neighboring affiliate, which was too far away for the station to relay from and for lack of affordability to videotape and delay the entire network schedule two to three hours later for broadcasting in the desired time periods.
The challenges of getting network programming if your station is in an isolated city were tough. You couldn't pick up any like neighboring affiliates to rebroadcast from and relay to your station. Some of the like neighboring affiliates didn't carry the shows you wanted to air. If you couldn't afford expensive videotape to delay the shows, you had to run the entire schedule off of the East/Central feed so the shows would start three hours early.
There were times when a TV station needed to use two videotape machines: one to air a delayed program the station taped earlier from the live feed, and another to record another show from the live feed, both at the same time. If a station could afford only one videotape machine, they had to tape some of the shows for slotting in later slots when the live network feed was dark.
In the mid 1950s for example, several affiliates in Seattle ran most of the network daytime schedules from 9am until 2pm live from the East/Central feed for shows that would run at NOON/11am CT until 5/4pm CT. At or after 2pm, the affiliates ran about two hours of the network shows that they taped between 7am and 9am on the East/Central feed that ran from 10am/9am CT until NOON/11am CT in those zones. The ABC affiliate ran the hour-long Mickey Mouse Club usually at 5pm. Morning and evening news shows and prime-time shows were taped earlier from the East/Central feed by videotape and played to match the times they ran on the Eastern time zones three hours later.
When the networks finally began their Pacific Time Zone feeds via phone lines and/or microwaves around the turn of the 1950s/60s decade, I guess CBS was the first network to do so, the daytime lineups were standardized at first to run the mid-morning shows using the Central Time Zone pattern, and the later shows on the Eastern Time Zone pattern at first, but shifted the later shows earlier so the entire daytime schedule (except for the Morning News and Captain Kangaroo) followed the Central Time Zone pattern.
NBC's Pacific Feed for daytime was unpredictable at first, but by the mid 1960s, the establised a uniform time slot pattern was established with Today from 7am-9am, then the first three hours of the morining shows from 9am-NOON, and the last three from NOON-3pm. In 1975, NBC shifted the last three hours to 12:30-3:30pm to match the time slots seen on Central Time.
ABC's Pacific Feed at first when it began followed the East Coast time slotting and I think they experimented by moving their shows earlier by one hour in at least Seattle briefly in the 1960s before shifting it back. What I'm sure about is that in April of 1974, ABC moved the range of its daytime schedule earlier by one hour but kept six of its shows from the Eastern Time slot pattern as they were established to be working against their competitors at the time. The change took over gradually as shows got canceled and new ones popped in, and once reruns of the Love Boat were shown at 10am PT (11am ET/10am CT), the entire ABC Pacific feed followed the Central Time Zone pattern.