You're generally correct about TNG, but I think that Worf's development and the machinations within the Klingon High Council roughly constitute a story arc that ran through the series.
Thank you, Ron Moore, who probably deserves at least a fractional share of the credit for the evolution of genre TV from the episodic structure of the ‘80’s and early ‘90’s to the serialized structure we take for granted today.
Hard to believe now, but at the time shows that embraced multi-episode character arcs and season-long plots ran a risk of being tarred as soap operas.
The closest thing that TNG has is the Lore and Borg episodes. Picard’s assimilation and the Battle of Wolf 359 has resonated across episodes and series. “The Best of Both Worlds” arc doesn’t fully end until s4e2’s “Family”.
Hard to believe now, but at the time shows that embraced multi-episode character arcs and season-long plots ran a risk of being tarred as soap operas.