One of the things I love that publishers sometimes do is to compile a compendium of a writer's work. Just about the entire backlist of Lois McMaster Bujold's Vorkosigan novels was gathered up in three-story compendia. Cordelia's Honor, Young Miles, up through Miles in Love and beyond. Jennifer Crusie's publishers went that a bit better: The Jennifer Crusie Collection: Tell Me Lies, Crazy For You, Welcome to Temptation, Fast Women, Faking It, Bet Me, Maybe This Time. There was already Jennifer Crusie Bundle: An Anthology with four other of her novels. I remember having The Past Through Tomorrow by Robert Heinlein. You can't find that as an ebook anywhere. Asimov's Foundation Trilogies was another.
I don't always wait for the publisher to get that greedy sparkle in the eye that says, "I can cash in on these books as though they were new!" Sometimes I give them a hand, just for personal use. It's their work - I just want it at hand in fewer files than usual. I was about to wrap up Bujold's Penric and Desdemona stories in a single mobi file when Baen reissued her stories in two trilogies, and there may be a deal for a third or fourth.
I do it with non-professionals, too. (That sentence doesn't sound quite right.) Uther Pendragon wrote a series of stories about Bob and Jeanette Brennan and their daughter, the Kitten. It was a pleasure compiling them all in a single Mobi file, and adding it to my Kindle. (It somehow got deleted and I need to recreate it.) 2022-06-18 18:34 I have just recompiled BRENNAN - A Universe from the Mind of Uther Pendragon. I'm preafrooding it for errors I may have introduced. There are 31 noted by the compiler, mostly links that I have killed by compiling. The cover for this project is two people in bed reading books. If you're familiar with the Brennans, you understand that everything isn't about sex - just mostly.
My current project is Grey Wolf's Variations on a Theme. It stands at around three books of 89, 116, and 102 chapters plus an appendix. I even made a cover:
Of course, I make covers for every project. This one is based on an incident in the second chapter of Book 1. I also compile webcomics into Graphic novels. It works best when they run serial plots like Grrl Power by Dave Barrack, but it's nice to just gather the output like Living With Hipster Girl & Gamer Girl by Jago DiBuja. It's too bad The artist of Too Much Information had multiple strokes. It looks like that one will never be finished.