That's interesting. I do the reverse. I have a trail of hundreds of mind maps and lists on paper, some of them probably recycled by now. I've always wondered if it would have been better to save them and review. I think I've lost a lot of work on some problems/ideas I wanted to explore that way. Probably forgotten a good number of problems I was interested in to start with. Mostly personal though - professionally, my desk piles up until I'm forced to review the usefulness of each piece of paper (still, the 'where's that sheet gone' dance is common).