Chapters are funny things. When you read a finished book, it's obvious where the chapters begin and end. Sometimes there's a big shift in time and place or the point of view changes. Sometimes it's just a natural division in the story. The chapters have to change where they do.
But during the first draft, it's not always so obvious. Sometimes I'll write a sentence that just screams out to be the end of a chapter. So I'll move on to what I assume is going to be the next chapter, until I realize that I'm still working on the previous chapter.
Sometimes I know where all the chapters will be before I start to write. Hailey's Bali Diary was always going to have 8 chapters. I could have made each chapter longer or shorter, but it was always going to be divided into 8. That's just the way it had to be. Shooting For Paris, on the other hand, just kept going and going. I had no idea how long that was going to turn out. The first draft had 50 chapters, each between 6,000-10,000 words. Chapter 47 clocked in at 12,000 words. It was out of control. To put it in perspective, Harry Potter books usually have 4,000-5,000 word chapters.
Of course, there are no rules. Anyone who follows arbitrary rules is following a formula. Formula books are the worst. Mark Twain has a novel with the shortest chapters I've ever seen. Stephen King has a novel that is all one chapter. Mark Twain and Stephen King might not sound like similar writers, but, like them or not, they both knew what they were doing.
My own point of view is that a chapter should be whatever it is. You don't try to cram your dog into the sweater you have. You buy him the sweater that fits. But publishers want shorter chapters. That's what sells. They, generally, believe that readers have short attention spans. People with short attention spans can read a few thousand words in one sitting. 12,000 words is unacceptable.
Someone once said, “Write your story the way it wants to be written. As soon as you look over your own shoulder and second guess yourself, you're doomed.” I'd attribute the quote, but I don't remember who said it, and Google isn't helping.