Deep Space Nine turned from being episodic to serialized, but I would prefer episodic.
If it has plenty of standalone episodes which don’t tie into the main story arc, then it ain’t serialized. DS9 had plenty of standalone episodes.
they had plenty of standalone episodes in the early seasons, but once the they got to the war with the dominion, it became serialized.
I wouldn’t say the entire show was serialized. There was a progressing story arc, but most of the episodes (even in seasons six and seven) were contained plots. Remember the baseball episode?
ok not all the episodes of the later seasons were serialized but most were.