Show pilots are a very tricky process. They are made, and even if they get a chance on the air, the vast majority of them fail within a few weeks. With other shows, they sometimes will build up a dedicated audience that will fail to keep the show alive long enough. Most of the time. In the case of Long Runners and shows where a hundred episodes is not that big of a deal, the celebration is sometimes in the form of "10 Year Anniversary" or something similar. But no matter what, remaining in the public view for five years is an impressive event in any form of media.