In Philadelphia, Westinghouse's KYW TV Channel 3 was notorious for preemptions. In the 70's, they preempted about 90 minutes of the NBC Daytime lineup, usually the 12 Noon hour and the 1-1:30 PM offering joining NBC at 130 PM for Days Of Our Lives. That 90 minutes had NBC shows that came and went. Until the end of 1976, WPHL 17 ran the preempted NBC shows 9-10 AM (when KYW was only preempting the noon hour). KYW also occasionally preempted a prime time NBC show with lower ratings for local specials or some NBC movies for a syndicated movie. They were running the NBC Saturday Morning lineup in its entirity though. From Winter to Summer of 1977 WKBS TV Channel 48 ran preempted NBC daytime shows at 930 AM, Noon, and 1 PM. They would run Name that Tune at noon, Lucy Show at 1230 which was syndicated and back to NBC show at 1 which was The Gong Show.
That Fall, 17 WPHL ran the preempted NBC shows Noon to 130. KYW TV then got worse with preemptions in the fall of 1980. They preempted the 10 AM to 1 PM time slot for Hour Magazine, People Are Talking, and News. Channel 17 ran NBC rejects 9-10 AM, 1130-1 PM, leaving out one of the shows. In the Fall of 1981, KYW was back down to 2 hours worth of NBC preemptions and they ran about an hour of NBC game shows out of pattern in late afternoons mixed in with syndicated game shows. They would remain like this until 1991 when they went down to preempting only one hour a day due to the fact that NBC was giving that hour back to affiliates anyway. They remained like this till they became a CBS affiliate/quazi O & O (eventually a true O & O after the Westinghouse merger. 65 WRBV/WJST ran some NBC rejects from 1982 to 1985. Channel 29 WTAF/WTXF ran some rejects until 1989 or so. After that Channel 40 WIldwood would be on most of the cable systems to make up for the preemptions (they cleared NBC's whole schedule).
6 WPVI also preempted quite a bit of ABC shows. Not as bad as KYW. They would preempt whatever ABC offered at noon for local news. They also preempted Good Morning America entirely from its 1975 launch until 1977 for Captain Noah and his Magical Ark which was a kids show mixing in pre 41 colorized Porky Pig cartoons, post 48 Bugs Bunny and Daffy Duck cartoons, Made for TV Popeyes, Mr Magoo, and Gumby. In 1977 they began running the 7 AM hour of Good Morning America and Captain Noah 8-9 AM. In the fall of 1978 as CHannel 17 acquired the Bugs & Porky Cartoons and 29 acquired the Popeyes, Channel 6 relegated Captain Noah to weekends. Channel 6 also began preempting the 4 PM ABC show in 1975 which was Edge of Night beginning in 1976. Channel 48 WKBS TV ran the ABC rejects 10 to 11 AM. Beginning in 1978, WPVI's rejects were 20,000 dollar Pyramid and Edge of Night. Beginning in the summer of 1980, WPVI preempted the 11 AM hour as well as the 4 PM hour. They ran Family Feud at 11:30 initially and at 10 AM eventually. That 11 AM offering was usually The Love Boat. Channel 48 ran those 2 shows 1030 to Noon.
In the Summer of 1983, WPVI preempted Loving, Edge Of Night, and Too Close For Comfort. Channel 48 decided to dump ABC rejects that May except for Too Close For Comfort with plans to drop that in the fall (unaware they would instead go dark end of August - that decsion being made July 14). Rejects moved to Channel 29 WTAF for a while and then to WSJT and then to NBC affiliate Channel 40 in Wildwood in the 9 AM hour and 4 PM slot. As an O & O they continued preempting the 11 AM to 1230 hour and a half. Finally when ABC canceled Ryans Hope, Loving began to be run on Channel 6 in 1988. Beginning in 1992 when ABC gave back the 12 Noon slot, Channel 6 began running 30 minutes of teh Home Show in 92 and then 30 minutes of Mike and Maty (which morphed out of the Home Show and replaced that show anyway). Finally in 1997, they began clearing the entire ABC schedule when the View premiered.
Saturday Morning cartoons were run in their entirety till 1978. Sunday Morning they ran the 11 AM hour from 930 to 1030 AM, ran 1030 in pattern and then Al Alberts at 11 AM. In 1978 they began preempting the 8 AM cartoon for Captian Noah which began at 730 AM. They also ran Captian Noah with Kids Are People Too Mixed in. At one point, they began mixing the 8 AM Saturday Morning 8 AM offering within the hour Captian Noah show. They also began preempting the 11 AM Saturday Morning offering for local public affairs in 1978. They continued this practice till the mid 80's. By 1986, they began running the 11 to 1230 PM Saturday morning cartoons from 6 to 730 AM. By 1995 they ran the Saturday Morning cartoons in pattern. What was so ironic about Channel 6 was after they became an O & O they continued to preempt ABC shows, though they no longer occasionally preempted prime time programs anymore. What happened was their owners Cap Cities bought ABC so Cap Cities had been running Channel 6 so they continued running it as they saw fit, while original ABC O & O stations wree run differently. It seemed the Cap Cities ABC O & O stations were run as their own seperate unit till Disney bought ABC.
Also Channel 10 WCAU preempted a small amount of CBS shows even as an O & O. This was only Saturday Morning and Sunday morning offerings. In 1975 WCAU preempted an hour of Sunday morning CBS public affairs offerings. In 1976 they ran only 30 minutes of the hour of CBS Sunday morning children's shows. In 1977 they preempted the entire sunday morning hour of cartoons. In the fall of 1978, they preempted the entire Sunday Morning cartoons and the 8 AM hour of Saturday morning cartoons. In the Winter of 79, they moved the syndicated Marlo Movie Machine show to Sunday mornings (which went to 30 minutes from 60) and began running the Sunday morning cartoons at 8 AM Saturday morning preempting the Saturday morning 8-9 AM offerings. In the Fall of 1979, they began running the Saturday morning cartoons in their entirity but preempted the Sunday morning ones. beginning in Spring 1980 they brought back the Sunday morning cartoons again. From the Fall of 1980 on WCAU began running the entire CBS lineup again.
In 1995 KYW became the CBS affiliate and then an O & O. They had begun preempting all but an hour of NBC teen shows and the Saturday Today SHow since its debut in 1992. But as a CBS O & O they ran Saturday morning news 6-10 AM (they ran this till Noon as an NBC affiliate). They ran the 10 AM to 1 PM cartoons in pattern. Then On Sunday Morning they ran the Saturday 8-10 AM cartoons from 7 AM to 9 AM Sunday morning. So they cleared the entire lineup but delayed 2 of the hours.