Being a "hoarder" (as my father puts it) of books, I would also reccomend the process of putting them out of sight for a while, and seeing what happens. I will go through them a couple of months later and realize that some of the books I can't part with, and others I look at and go "What what I THINKING?"
Done that
Kept just the most valuable ones - the thing is that i received from my parents really valuable collections and sets - of encyclopedias, atlases, whole editions of these and that classics... ugf. I don't keep chick lit, neither self help books, cook books (apart from very fancy/expensive editions) - any of that, just really worthy stuff, but myself also i gave crazy amounts of money for collectibles and some rare sets and what not...
Mine is a nice collection, really, and its nicely arranged and all - its just that it would be more suitable for some castle with maids who'd undust it and all, and with some lazy nobleman who'd have time to read for hours... lol, i don't even live here best part of the year!
Actually - the crazy thing is that my cat grew to love that room - as its calm and dark, and noone's there - that's where she goes for daily retreats .
For some reason, to me decks and books don't go together (don't ask me why, i don't know ether - but if i take the decks there to me it feels as if they'll start to scream
) so those babies are in three shrines in the living room (and oracles divided in other two)... its enough.
But even if i had all the room in the world, i don't want that many decks - i have collection of Swarowski figurines , Bohemian glass figurines, Herendy porcelain and Chinese vases (did i mention paintings?)... and it all is very nice, but requires hours of maintenance.
It takes me at least one whole day a week just to keep those undusted and tidy.
But, not to hijack the thread - for myself personally i don't see a point of having a 1000 or more of decks simply because those that i really like are not that many at all.
We had such discussions before - and basically the real collectors among us love all their decks - pretty or not, deep or not or whatsoever, someone said here that they feel their decks like children or something and that it would be unjust to favor some ...
But, as i said before - i am cruel - no mercy here! Just the loved ones stay, the others are given away!