The difference between Champloo, Bebop, shows like that, and things like Naruto is they're not based on manga, which is why they end quick. I considered going into this earlier, didn't see much point in it but here goes: all the long shonen shows are based on comics that are continuing as episodes come out. DBZ was the earliest, and most disastrous, show to run into the obvious problem. They ran out of source material in the middle of the Frieza arc, mid-fight, and there wasn't shit they could do about it but stall for time. A lot of time, as it turns out. More recent shows pace themselves with filler arcs, which are universally bad, and as a rule not worth watching. It's the nature of the beast.
I would argue that out of the three biggest continuous shonen shows, Bleach, Naruto, and One Piece, only Bleach is doing badly. Naruto and One Piece have both had arcs that have dragged, but take them as a whole (minus filler arcs) and they're well worth watching, and will probably continue to be so.
