I used to use an old scrap of binding over and over as my leader/ender, but then I finally grasped the concept that I could be sewing two quilts at once with no more effort than I used re-sewing the binding scrap. Now I prep a planned project until it's at the leader/ender stage. Currently it's a log cabin pattern by Thimbleblossoms called Sweet Escape. I don't have scraps available for a random leader/ender project. Eventually I hope to deal with my scraps and get them into a working system, but not until I finish my planned projects.