I find it amazing, too, especially in the first two seasons. In a recent interview posted on youtube, Danny Epstein (drummer for Joe Raposo's band, and eventual Musical Coordinator for the show) explains how everybody was putting in 12-to-16 hour days just to get the show ready for the November 10 premiere. A lot of the Muppet segments were cranked out in one or two takes. On top of that, Danny and Joe Raposo also had another job playing music at WNEW/Channel 5 across town. This was their regular job that they were encouraged to hold on to, just in case Sesame Street didn't work out.
But it's remarkable how everybody was committed to giving the show their all. They knew it was going to be different. They knew it was going to be revolutionary. It was a total labor of love. and the reward would be us here today, still treasuring moments they created nearly four decades ago. Makes all the effort worthwhile, doesn' it?