I store orphan blocks and unfinished questionable items in a large pizza box. I periodically (once a year?) get it out and actually do throw away old projects that I'm not crazy about. Sometimes it takes a few years before I eliminate something, but it does happen. Sometimes I simply remove (cut off) part of a project and it then begins to look do-able. By letting a project sit for a year or two, I gain new perspective and can either let it go completely or work on it again.