This is something that's just recently crossed my mind regarding skits and inserts of the early 70s... It seems like quite often, the skits would consist of multiple characters, five, six, or more, and of course, with that many characters, there's bound to be at least that many performers as well... however, when it comes to the voices, they're usually dubbed by just Jim, Frank, and Jerry. Two that come to my mind are "The King's Problem", which has six characters: the king, the king's aide, the tallest person in the kingdom, the fastest person in the kingdom, the smartest person in the kingdom, and the smallest personin the kingdom; Jim voiced both the king as his aide, Frank voices the tallest and smallest people in the kingdom, and Jerry voiced both the fastest and smartest people in the kingdom. The other is Herry's alphabet secret, which involves five monster characters like Herry and Grover, and AM monsters Pamela, Fenwick, and Rosemary; Jerry voices both Herry and Pamela, Frank voices Grover and Rosemary, and I'm not sure who voiced Fenwick, but I believe it was Jim. It sort of makes me wonder why the extra trouble was made to dub the voices, considering the early 70s is obviously when the Muppets were expanding: 1969 had just Jim, Frank, and Caroll (occasional assistance from Jane and John Lovelady), but soon afterwards saw Jerry, Fran, Richard,. and others... matter of fact, Fran was also a voice artist, surely she could've performed and voiced some of the above mentioned characters.