I have heard Laverne & Shirley used The Odd Couple set, but found no real evidence of this. If you find the unaied pilot fo Laverne and Shirley you will see they used the set from Fonzie’s apartment from Happy Days (this was filmed after a Happy Days episode one night)
The school sets in Saved By The Bell can be seen in That’s So Raven!and ICarly
The Miller/Boyett shows had similar sets which serious fans could recognize
The Bewitched interior was also used in Gidget and I Dream of JeannieÂ (and an old Jerry Lewis movie)
704 Hauser was an intended spin-off of All in the Family in the sense that the character was the opposite of Archie Bunker and lived in his house. The same sets from the old show were used, just modernized.
Of course some shows do this within their own series. Boy Meets World reused an apartment set as well the school hallways and classrooms. When Benson stopped being budget director the set for his office vanished, but was reused as a psychiatrist office in a later episode. And many times on shows like Frasier or Will & Grace they will just re-dress the main set to represent a different apartment in the same building.
Not a sitcom, but Star Trek did this a lot, with The Enterprise, Ds9, Defiant, and Voyager standing in as other vessels (and stations) even in other shows (and the movies)
This is just a sample of course. I am Sure there are others I didn’t mention. If I have forgotten any let me know, this is kind of thing fascinated me. Not sure why exactly.