Most of these later episodes focus on one or two of the characters other than the main two, Zeb (James Arness) and Luke (Bruce Boxleitner.) Zeb and Luke are by far the most interesting characters and Luke has an ongoing story-line that isn't satisfactorily resolved by the end. The first three sets had ongoing story-lines woven together but in the last two sets the stories are stand-alones.The last two episodes deal with Chinese immigrants and slave trading of women in Mexico. The subjects are interesting but not what I want from a western.
Zeb is Luke's uncle. He's a "mountain man" of great experience. He's 6.7" tall and an inexorable force in pursuit of his principles and anyone threatening his family. Luke is a young man on the run after the Civil War. He gets a reputation as a gunfighter and has some hairy adventures, sometimes rescued by Zeb. In the fourth and fifth sets of episodes he's become respectable, which makes him less interesting. He also cuts his lovely long hair, to my dismay.
The first, second and third sets (the series don't coincide with the DVD sets) are the best, the third in particular being exciting, leading to a showdown between Luke and the sheriff who's been hounding him for years and between Luke and a gunfighter who blames Luke for his brother's death. Luke and another sheriff's daughter are in love, but she's dropped after the fourth set. It's a pity because they have a lively relationship full of passionate arguments and passionate making-up. I think the couple have excellent chemistry and their romance would have been a good subject for further episodes.
I'm glad I bought this series. I'll re-watch many episodes.