I heard that most japanese collectors have 
collections that put everybody else's in the world 
to shame. Not surprizing I guess. Like they say in 
real estate, location, location, location! One of 
the guys at Anime Gambit told me he knows a 
collector in Japan who has a collection so big that 
he doesn't just have a cel or two from a particular 
series, but has a cel from almost every scene, from 
every episode, of an entire series! He said that he 
has binders labeled for particular episodes! It 
seems it would get to be TOO much at that point.

 Having worked in record stores for several years, 
I knew people that had MASSIVE collections of 
music. Thousands upon thousands of CD's and albums. 
It occurred to me that you couldn't reasonably 
listen to that much music even if you devoted a 
lifetime to it! I suppose you could argue that cels 
are different (which they are), but that seems like 
a little too much to me. That's just me, however.