As my years as a fan wears on, I become more disillusioned with stories strictly limited to demographics. It's the most prominent reason for my declining interest in anime since 2008, where companies have had to pare down productions to their core audiences. Manga is thankfully more malleable, where even genre/demographic stories manage to remain free of conflicting visions of production committees.
Andrew brought up Kekkaishi as a fair comparison to Bleach some time ago, and it captures the two publishing approaches well. Unless one has a thorough, long-reaching plan and understanding of his story, characters and setting -- Eiirchiro Oda of One Piece being a popular example -- it's difficult to maneuver your series around the editorial policy of Weekly Shonen Jump while maintaining quality. Kubo Tite has admitted that he doesn't really think ahead, and explains why readers endure bloated arcs with endless amounts of fodder fighting. Yellow Tanabe, consciously or not, consistently grasps the appeal of Kekkaishi, and has never had an arc extend beyond two volumes. At eighteen volumes the reader knows little more about Kokuboro and the Shadow Organization than we did at nine, but it's all a MacGuffin for Tanabe to indulge in creative monster designs and characters that we quickly grow to care about. Volume seventeen might be my favorite of the series so far, effortlessly weaving these two threads -- Yoshimori's strained relationship with his brother, and a traitor of the Shadow Organization returning as an ayakashi, seeking immortality -- together.
The opening volumes (ten and eleven) of the Paris arc in Nodame Cantabile are rough, unable to sustain the satisfying urgency that came with Chiaki's key decisions regarding travel abroad and Nodame in volume nine. Amazingly, Tomoko Ninomiya seems to correct this with the near-exodus of the always entertaining Stresemann in volume twelve, moving at last past the first round of competition and exhibition of characters to focus solely on their troubles in the City of Lights. The two major draws of the series resurface stronger than ever: the blurred line between the shojo and josei demographics, and the romance supplanting the comedy rather than the drama. Even when Chiaki's insecurities of abandonment boil, the presentation is always low-key: a fight in volume thirteen between the main couple is staged at night in front of an curious crowd, tempers rising as Nodame drop kicks Chiaki after being insulted. Just as swiftly, the argument charmingly resolves itself a few pages later.