This informative article is not directly about sitcoms, but so many of them in the 1970s were videotaped that it seems pertinent.
“Video editing pioneers didn’t have the simple pleasures we take for granted today. As you may already know, they didn’t have things like time code, computer-based editors or Video Toasters. But did you know they also didn’t have electronic editing, audio dubbing or even slow and fast motion picture search?
The first editors worked with the equivalent of a chisel on stone to put their ideas together on tape. They could only dream about many of the features now taken for granted by videomakers.”
For more on the history of videotape editing, see this Museum of Broadcast Communications article: