Before the show went from a single camera/laugh track format to multi-camera filming in front a studio audience, in the third season, there was a single episode shot in the second season in front of a studio audience that was used as a test ("Fonzie Gets Married"). Below is a link. I'm curious: In this episode, the living room set that was designed for this live audience test is almost identical to the original single-camera set. They just removed the "fourth wall" and expanded the side walls a bit for visibility to the studio audience. So why in the third season did they design a completely different set that looked hardly anything like the original (e.g. the front door is no longer by the staircase)? It made it seem as if they were living in an entirely different home. It seems more logical for them to have kept using the set from this test episode.