So many things seem to be in series, sometimes things that should only be one are often more. It seems like everything in SF and fantasy is coming out in multi-book epics these days. Then I stop and think, this is not a new development.
I remember reading early Asimov stories and he had his robots series and his Foundation series, not to mention his attempts to unite them all, and of course Tolkien and Middle Earth.
Even one of my favourite books as a child, The Hitchhiker’s Guide to the Galaxy, ended up being a series. The Colour of Magic by Terry Pratchett seemed to be a standalone, then he wrote some more and some more and suddenly it wasn’t for which I remain ever grateful – speaking of which, I don’t think I’ve read any since I first read them. One day, I must embark on a full Pratchett re-read; re-reading the entirety of Pratchett seems somewhat Odyssean.
Speaking of childhoods, I read so many series: The Hardy Boys, Nancy Drew, Alfred Hitchcock and the Three Investigators, Trixie Belden, Biggles, and many, many Enid Blyton books. In fact, speaking of Biggles, I have finally acquired Comrades in Arms by Capt W.E. Johns which includes stories from each of his main character sets: Biggles, Gimlet, and Worrals.
A couple of years ago I read a then newish SF writer, Becky Chambers and her first novel, The Long Way to a Small, Angry Planet, which in turn has had a sequel, of sorts. At what point do sequels become series? Speaking of which I must get round to reading more from her.
Oz author, Daniel O’Malley wrote The Rook – which was turned into a TV miniseries -and then a sequel, Stilleto. I am eagerly awaiting the 3rd book and have been for a long time. Though Book 1 came out in 2012, book 2 in 2016 so I have some hope that book 3 may appear in 2020. Some.