If I kept them I wouldn't be able to get out of the house!
I used to keep all of them. Then one day I had a major chuckout and filled no less than 4 bin bags... These days I normally only keep the ones fit for a portfolio or that I just really like... and even then sometimes it's just a digital file.
I do have a lot of old doodles filed away on my shelf though.
I doodle in sketchbooks so it's easier to keep them contained. I've been doing the daily ones for Amber, up on Design Splat, been fine keeping up with it so far (except when I went on holiday) but now I'm back at uni I'm probably going to end up doing more "simple" ones and no decent ones just because of time
I started a project similar to this a couple of years ago. The idea was one random picture taken on my phone & one word each day collated into a book. I ditched it after about 3 months as I'd started going out of my way to find pictures and that's not what the concept intended.