Long-running series tend to be great well-done pieces of work, but they can also fall into the trap of not knowing when to quit. Shows that run on for too long tend to experience either a dramatic drop in quality or simply decide to spin the wheels.
In the West, sitcoms like That 70s Show, MASH, and Scrubs, all suffered from lackluster final seasons due to cast departures, script changes, or a general weariness of running such a long-term show. The Godfather Part 3, will always remain a strange postscript from the first two installments for this reason. In regards to Anime, there have been many mangas and series that have been criticized for overstaying their welcome, or not ending when they should.
Things like the 2nd half of Death Note, Inuyasha, Dragon Ball’s Buu Arc, Bleach after the Aizen storyline is concluded, and current running series Food Wars have all suffered for not knowing when to quit on a good note. There is a debate on whether current fan darling Attack on Titan is suffering the same fate. There are many reasons for this, either due to editorial mandate, a desire to remain published, or general burnout and disinterest in the work. These series and many more have had part of their legacy be sticking around for just a bit too long. Even Naruto, while having a satisfying conclusion suffered from having plotlines and villains remain long after their storylines should have naturally concluded.
The series we are looking at today doesn’t suffer from this and actually succeeds because it decides to end when it finishes its story. Let’s take a Shallow Dive into Kentaro’s Yabuki’s Black Cat