It was not unusual back in the 70's and 80's for PBS to air a lot of independent content that had odd run times. Specials and movies could end with 10 to 20 minutes dangling to the next hour.
In 1982, I first saw a cool animated short from the National Film Board of Canada (NFB). Today that video appeared in my YT suggestion list!
Pick me up off the floor - this animated short is from 1971.