I am the same way, if the piece looks large enough to be used on something it stays. I have a scap bucket of balsa and spruce stick stock. A bin with scap ply and a box of scrap balsa sheeting. I usually find the need to go into these scrap bins several times during a build. When I clean up at the end of the build anything worth saving goes into the appropriate bin for the next build.

My wife says I am a hobby pack-rat
Anthony