This comes from a TV Guide in 1968, just as the new fall season arrived. I found the picture at a website called Television History. It shows a grid with all of the prime time shows on the major networks:
If you want to know what was different about life for a 15-year-old American in 1968, here is one example. Three channels to choose from, all over-the-air free-with-ads. The total number of prime-time series was smaller than a list of the prime-time series today for any specific time/day.
As for what I watched: Saturdays were CBS until 10:00, although if there was a rock and roll act I wanted to see, I would switch to Hollywood Palace. Sunday was also CBS: Ed Sullivan, Smothers Brothers, Mission Impossible. Monday was tough, since the second half of The Avengers conflicted with the first half of Laugh-In, and there were no VCRs in those days. Tuesdays I’d watch Red Skelton, or nothing at all. Wednesdays were totally cruddy. Thursdays began with ABC comedies The Flying Nun, Bewitched, and That Girl, followed by a switch to NBC for Dragnet and my dad’s fave, Dean Martin. Finally, Friday had The Wild, Wild West.
The truth is, Robin and I started going together in late September of that year, so I spend most of these evenings talking to her on the phone.