I just took the Scrap Therapy class a couple of weeks ago and enjoyed it. But right off the bat, I did not adhere to their three sizes of scraps. I ended up cutting my scraps into the largest workable size because I hate to throw anything away! I also ended up with a lot of strips.
What the class did, however, was to get me to take care of the scraps right away rather than throw them in a box to do something with later. I found myself cutting blocks in sizes of patterns of quilts I enjoy doing, such as the Yellow Brick Road, etc. Then the scraps are sorted, not so much according to size, but rather according to type of project, if that makes any sense.