I find narratives stressful when I don't know what to expect so I am much happier reading a story when I know what's going to happen in it - then it's about the experience of the narrative instead of worrying about what might or might not happen next.

I pretty much agree with everything in this comment but particularly with this. And it's not just the narrative, roughly knowing what will happen makes it possible for me to enjoy the craftmanship of the writer in a way I wouldn't be able to if I were focused on worrying what would happen next. In other words, it's the journey itself that interests me, not the goal.