I don't keep a journal, but I do keep a timesheet, jotting down the start and stop times each time I work on a project. I do that because one of the first questions people ask when viewing a finished quilt is "How long did that take to complete?" Now I can say 36 hours or whatever rather than about 3 months give or take. I try to include that information on the label if the quilt is for someone. I do keep a notebook with a picture of the finished quilt along with a notation of where the pattern came from and scraps of fabric or a leftover block (Kind of like a quilt scrapbook.).