B5, B5, B5... Wow! Did everyone here watch B5?
For the record, I did too.
I even watched Season 5. (But only once.
)
As for being part of the story arc, I remember J. Michael Straczynski talking about episodes and elaborating on those that were critical to the arc and those that were not. If I remember correctly, less than 1/2 of the episodes were key for the arc.
That's why Season 4 got so intense. They were convinced that there would be no Season 5 so they pulled all of the S5 arc-critical stories into S4. That's what blew-up S5. They had a season but the story arc was complete.
Sorry for the B5 digression.
Bob