I can't think of another part that begs the question "Where is this going?" more frequently than Jojolion.
Parts 1, 2, and 3 are straightforward as hell. Part 7 gets off to a shaky start as Araki tries to figure out what he wants SBR to be, but once he gains confidence, it's full steam ahead.
Part 5 is fairly straightforward but zigzags when the emphasis shifts back and forth between Diavolo's loyalists and Nero's hit squad. Then it wobbles like jello as it approaches and enters its endgame.
Parts 4 and 6 are the only ones I would consider to be in Part 8's ballpark in this regard. In the case of Part 4, it's Araki trying to balance "advance a main plot" with "showcase Morioh as a living, breathing town", so at least I understand his objectives when writing. In the case of Part 6... eh, this one is a pretty big hodgepodge, so I wouldn't knock anyone for thinking Jojolion is more convincingly written.