I got you beat as far as how long you wait. There's a Victorian empire nonfiction trilogy that I've started countless times. I almost finished the first book once. I found the first book at a used book store in ABQ in the early '90's or maybe earlier. I've been waiting for the time when I can really dive in and stay there long enough to finish all 3 vols. I love the writing and the stories and the viewpoints and when I discovered the orig. edition had pictures, I finally got a hardback, slipcovered reprint from Abe Books. Looks like its time will be arriving in a month or so! But that's an exception. I like finishing series. I have a bigger problem starting them!