A hundred years ago the nature of the novel was changing. In the mid-nineteenth century, novels were so expensive, stories were broken down into sections and published in monthly magazines. Which meant most of novels had not been finished when the first section was published. As prosperity grew, the novel became affordable and those serial publications slipped away.
The publishing of the novel is continuing to change with the rise of ebooks. Several authors, I won’t name names because I think they are nothing but money hungry blood suckers looking to exploit their readers, publish a story in sections. So, you read what you think is a complete story and it turns out to be a 10,000 word section that ends with an instruction to buy the next part if you want to know what happens. I am not a fan of this serialisation because it is rarely upfront. The author rarely tells you that the story is incomplete and instead presents their work as the more common form of serialized fiction, the novel series.
We live in a world that embraces sequels so readily that the majority of authors don’t see novels as single stand alone forms of fiction, but merely the first part in a series of novels. Ebooks have provided a pace to novel publication that means it no longer takes months, even years to get a novel published. You can do it in an afternoon.
Expectations have changed. Living in a world of TV shows where we follow characters from one situation, we expect our investment of interest to be returned with more stories. Possibly because we are lazy, possibly because we grow attached to characters.
In the past, several authors had novels that used the same characters, but the sense of continuing series and consistency were never prime concerns. Raymond Chandler didn’t set up a character in one novel that he then returned to later in another novel. Each novel was an isolated story separate and distinct from the last. Consistency between novels was irrelevant. Ian Fleming created a continuing cast of characters, but consistency was hardly high on his agenda. With Bond’s consumption of cigarettes and alcohol, he would have ceased functioning after two novels.
So, you are asking, novel series, good or bad? To tell you the truth, it just is. It is a more prominent part of current published, but it isn’t new. Just look at Asimov’s Foundation series. But then Asimov was so good, he could have done anything and made it work.
How we read novels have changed. How novels are published have changed. What hasn’t changed is the difference between good writing and crap writing. The only obstacle we have is increased volume has made getting to the good writing more difficult, but that is a discussion for another time.