I was watching Dallas (1978) on DVD and was thinking about thoes shows that had these episode perviews before each episode. It seemed like there was a lot during the late 70s through the 80s. Anyone know why they use to do this, & how long that fad lasted? I think I know why they stopped, because it was dumb, but still its interesting that they once thought it was a good idea.
I can name a few.

Dallas
Dukes of Hazzard
Magnum PI
later seasons of Hawaii Five-0
Murder She Wrote
Matlock
A-Team
Macgiver
Remington Steele

But I'm sure theres more. Please post more if you guys think of any.
PS I try googleing this but don't came up with anything is there a keyword I should have used?

The Flinstones did something similar, but they only showed one scene before the credits

Hardcastle and McCormick
St. Elsewhere

In the 70's and 80's,sitcoms only employed this in the cases of "two parters".Of course nowadays,if the situation in a comedy necessitates more than 30 minutes,they just run it as a whole hour.Interesting thread.