I kept about 6 years worth of scratch paper in about a dozen 3-ring binders for about 6 years after the last one (I moved to a job with less need for hands-on technical work). Apart from numbering, periodically summarizing (like every 4-5 work sessions, each usually 10-20 pages long) dating and indexing all of them, I did no other organization. In all I had about 2000-3000 pages of archived notes at the peak. I never did like notebooks. This was all one-sided discarded computer print-out paper.

From my use of this stuff, I'd say the half life of a sheet of paper (in terms of likelihood of reuse/referral) is about 6-7 months. I.e the probability that you will ever refer to a sheet of paper after writing on it is chopped in half every 6 months or so. It never decays to zero, but at some point a pile of paper decays to the point that you should toss it. Of course this assumes review of old work is part of your work processes. If it isn't, it should be. Hugely valuable.

There is plenty of delayed value. I've often gotten a new insight from piece of paper months after I first scribbled on it. It is also very useful for process analytics. See my post:

http://www.ribbonfarm.com/2008/0...

These days I am much less organized in private, since I do so much of my thinking in self-documenting public ways (i.e. blogging). I don't do much technical thinking these days, but if I did, I'd use a blog and simply take pictures of my scrap paper with my iPhone and blog it (writing, diagrams, equations, all together, still works best on paper).