For most of the series, Jerry Seinfeld at the start and end of each episode.
Jerry Seinfeld’s stand-up gigs appeared in every episode until season 7, where a few installments, such as “The Engagement,” excluded them. Then, suddenly, season 8 stopped including Jerry’s stand-up altogether, with the episodes thereafter typically beginning with a stand-alone cold open and ending with another bit that rounds out the conflict. While this largely went unnoticed as the pull for Seinfeld was the hijinks and dynamics among its characters, getting rid of Jerry’s stand-up in season 8 was primarily due to a change in leadership following Larry David’s exit as showrunner.
After serving as showrunner, co-creator, and lead writer since the premiere, Curb Your Enthusiasm’s Larry David left Seinfeld following the season 7 finale. Following David’s exit, Jerry Seinfeld assumed his roles, serving as showrunner, writer, and actor in seasons 8 and 9. With Jerry’s responsibilities to the show increasing, he decided to concentrate his writing efforts on the overall episodes instead of his stand-up bits. According to Seinfeld’s season 8 DVD commentary, Jerry nor the other writers could dedicate enough time to his stand-up performances in each episode, so they decided to remove them altogether.
Larry David’s departure from Seinfeld also led Jerry and the remaining executive producers to take a wider look at what was and wasn’t working. Paired with Jerry’s need to focus on writing for the show rather than the stand-up performances, Seinfeld realized that making room for the stand-up meant plenty of jokes and bits from the characters were being cut from the episodes. Since the show primarily relied on the dynamics of Seinfeld's main cast and characters for its comedy rather than Jerry’s stand-up, the series made the decision to cut the stand-up in preference of more organic gags from George, Elaine, Kramer, and Jerry.
Proving how instrumental Larry David was to the comedic beats of Seinfeld, Jerry’s stand-up routines finally made their triumphant return to the series in the season 9 finale. The series finale saw the return of Larry David to the writing team, allowing Jerry the opportunity to reintroduce and write his stand-up performances that had been so heavily present in the first seven seasons. While Seinfeld’s season 9 finale remains controversial, the last few moments still cleverly call back to its ever-lasting nostalgia as Jerry performs stand-up for his fellow inmates - truly proving that some things never change.