Damon has said countless times that in Seasons One through Season 3, Within the episodes, the story takes a step forward and two steps back, cycle repeats... How do we distinguish these steps from Story episodes needed from filler.
I think wee should make a page of what each episode does to the overall story line:
I.E. In Exodus, Locke, Jack and Gang go get the dynamite from the black rock, while Michael and them set sail on the raft.
While stories like "...In Translation" and "Outlaws" do nothing for the story.