Repetition takes different forms, with some readers unaware of what's happening. When I worked as a librarian, the
Mills & Boon romances were popular, with some people reading only them. As a profession, we were glad that they were reading at all, and the theory went that if they started with something easy then they might move onto more challenging stories. But ardent fans of these bodice-rippers stuck to them like glue.
The sameness of the plots was given away by readers marking the books they borrowed with secret codes, their own special signature on the corner of the flyleaf for instance, as a way of avoiding reading it again. Some endpapers carried multiple glyphs, making them look like a wall full of graffiti.
One old lady commented to me that the book she'd just returned felt familiar to her, as if she'd read it before, but that couldn't be so, as her initials weren't marked within. I had a look at the copyright page, seeing that it had been published five times before over the previous 40 years with different titles.
She could have read the same story many times before. This was one of the first indications to me that a book is essentially a product, there to be marketed and sold for a profit, even if it means changing the name over time to attract new buyers.