While the access rule ended the practice of a 7:30/6:30 start
for primetime (and the networks chose it; the FCC didn't mandate
it), there was a time when ABC was the only network programming
entertainment shows at 7:30. That was in the first half of the '50s,
when CBS and NBC each aired 15 minutes of news and 15 minutes of
music from 7:30-8. In the 1954-55 season, though, ABC had three
of its highest-rated shows airing at 7:30: "Disneyland," "The Lone Ranger,"
and "Rin Tin Tin," prompting CBS to move the news to 6:45 (or 7:15 depending
on the station) in the fall of 1955 and begin programming entertainment shows
at 7:30; three clicked that first year: "Robin Hood" on Mondays, "Name That
Tune" on Tuesdays, and "Sgt. Preston Of The Yukon" on Thursdays. NBC held
out until 1957. (In the early '50s "Kukla, Fran And Ollie" aired on either NBC or ABC
from 7-7:30 or 7-7:15, depending on the year.)
Remember, too, that the first year of the access rule there were a few exceptions
to the 8-11 primetime. Tuesday has already been mentioned, but only CBS and NBC
programmed 7:30-10:30 Tuesdays in the 1971-72 season; ABC got a reprieve from the
FCC to continue airing "Mod Squad," "Movie Of The Week," and "Marcus Welby, M.D."
from 7:30-11. In exchange, it gave back 8:30-9 Mondays, where coaches' shows aired
in many NFL cities. Similarly, NBC got to keep 7:30-11 Sundays, mainly because of Disney,
and gave back 10:30-11 Fridays. I've put this up before, but the first year of PTAR looked
like this:
ABC: MON 8-8:30 ("Nanny And The Professor"), 8:30-9 (local), 9-conclusion (Monday
night football)
TUE 7:30-11 ("Mod Squad, "Movie Of The Week, "Marcus Welby, M.D.")
WED-SUN 8-11
CBS: MON, WED, THU, FRI, SAT 8-11
TUE, SUN 7:30-10:30
NBC: MON, WED, THU, SAT 8-11
TUE 7:30-10:30
FRI 8-10:30
SUN 7:30-11 (Disney, "The Jimmy Stewart Show," "Bonanza," "The Bold Ones")
In the fall of '72 ABC was 8-11 every night; CBS and NBC were 8-11 every night except Sunday
(7:30-10:30). ABC tried a 7:30-10:30 Sunday primetime in the 1973-74 season, then went back
to 8-11 the following year. In '75 the networks got 7-11 Sunday on condition that the first hour
be either children's or public-affairs programming (a factor which would help "60 Minutes" rise to the
top of the ratings).
Officially, PTAR no longer exists but ABC, CBS, and NBC have continued to adhere to 8-11 Mon-Sat,
7-11 Sun. Fox has settled for 8-10 Mon-Sat, 7-10 Sun (I think this is because some of its o&os, once
owned by Metromedia, already had successful 10 PM newscasts).