I used to keep track of everything I drew. But once I started art school I was drawing a ton and the drawings would pile up. Especially the life drawings, animation paper and brainstorm sketches. Most of it's crap since it's just sketching. Now the only stuff I keep is finished work and sketches I like or might use in the future. When I'm done with a sketchbook I throw it in a drawer, but I don't scan or photograph it anymore like I used to.
Even with my Deviantart gallery, I deleted most of the old art because it was horrible compared to my recent stuff. I notice some people upload everything they do and have hundreds of images on their blog or website, but some of the best artist have only 10 or so. Sometimes a great artist uploads something bad and I wonder why they would do that, why not just move on to the next thing and try to do a better job?
I feel like I'm better off not being attached to my drawings and keeping up the momentum to make the next project better. Even though the process work is important, once the project is finished it served it's purpose and is not needed anymore. For me the final is the most important.
Do you guys like to keep track of your old art or toss it and move onto the next thing. And if you do keep it, for what reason? Maybe it's more useful for certain artists to keep old process work than others.