Should an anime continue past 30, 50, or 100+ episodes if it remains popular or profitable, or should it stay small and tight, with a finite plot and a pre-planned, limited number of episodes, possibly using movies or OVAs to tie up loose ends?
To be fair, though, at least in terms of Bleach, the manga itself has strong parallelism occurring in it between the two most important storylines which means similarities are bound to happen, and there's approximately 80 or so episodes which don't come out of the manga at all and were just cooked up by Studio Pierrot to milk all that they could out of the anime's dedicated viewers (off the top of my head, the two Bount arcs, the short 12 or so episode filler around the 130s, the recent 22-episode Amagai Shuusuke arc, and the two buffer episodes between finishing up the Nnoitra fight and Turn Back The Pendulum episodes). The latter means that the meat of the series rests in a decidedly smaller number of episodes.It's usually (?) not possible to continue a story beyond 200 episodes (anime-wise) without repeating the same plot device again and again.
Anything that goes over 200 is a bit too much for me.
but as Qyo27 said, the manga is long. In fact, a lot of manga-based animes end with either an anime original ending or gets cut off with no ending... so really, what is too long?