Chapters

What is the correct way to structure your book chapters? I’m easy, so I can read short choppy chapters or long ones just fine. I recently read a book that was written in three parts. I was so into it, I didn't even realize until the end there was only three chapters. And what about naming chapters. As a reader I hate this, I feel its an intrusion from the writer. Yet when I write I always try to sneak them in, and only because the reader part of me is stronger than the writer part, am I able to remove them. Browsing the various forums I'm trying to actively participate in, people can get into quite heated discussions about particulars like this. 

As I writer, I too overly think something that should be simple and instinctive. As a reader I’m easy every which way ;)