No major series by Rumiko Takahashi has ever really ended, they basically go on forever. I was never a really big Takahashi fan, and this explains why. It gets really old after a while.
But that's a whole different story from the likes of DragonBall Z, Naruto and others. Forget that beginning/middle/end logic, they're always stuck in the middle. Painfully padding out story arcs and recycling animation is an alternative to that classic violence that the PTA groups in Japan were stomping out. Gone are the brutal and wicked asskicking works of Gatchaman and Devilman (who usually get their jobs done in one episode), and here to stay are Goku, Naruto and their buddies spending the whole episode struggling in pain while the villain(ess) statically watches on in schadenfreude and makes remarks. There are only two punches and one kick per episode before this whole state of affairs starts again! Yawn.
Takahashi's works are more like an American comic strip. When a story ends, it's always back to square one. I think she loves her characters too much to want to see any of them go. Not that I blame her.
Kind of like Outlaw Star, in a way. It ended, but the "ending" of that series dragged on and on so much that it drove me absolutely crazy! The final episode ends at the middle (which is rather dumb), and the last 15 fanservice minutes is spent on the characters trying really hard to say goodbye (as if the creators didn't want them to leave). JUST SAY GOODBYE, ALREADY!!!
Even Cowboy Bebop had a better ending.