when you’ve lived a while, you realize it’s very hard to maintain a great show past the first season. Or the first movie.
The very rare show or movie has a good sequel.
Even if the sequel is good, by the third in the series they are out of ideas and the magic is gone.
That the problem with American series; they run too long, the premise gets exhausted and the show turns into a soap opera.
The Brits often produce six or eight great episodes and leave it at that.