Chapters are a funny beast. Unlike... oh, I dunno, every other aspect of writing, there isn't much in the way of guidelines or rules held up by those who have come before. Long, short, titled or no, labeled with POV or no, etc etc. Everyone just does what they please and nobody tries to claim any one way as a general standard.
At first that was a bit unsettling. Years ago when I went hunting for that exact advice, I couldn't find much. Heck, I couldn't find anything at all. What? A topic that no visionary had expounded on? Is there nothing in the Chicago Manual of Style that could be of use here? WHAT DOES FRANZEN WANT ME TO DO?
In the absence of internet-approved guidelines, I had to formulate some of my own. The breakdown comes in three general flavors: Chapters with Titles, Chapters With POV Labels, and Chapters with Neither Label Nor Title.
The last one is the simplest, as you don't need to think about much when starting them. This is the only chapter type I've used thus far in my own writing. They end up breaking down roughly by POV and chronology, though there are exceptions. I admit it is a bit messy, though it allows for lots of freeforming with the chapter structure itself. Also, my chapters tend to gravitate towards a standard length, though I don't enforce this consciously.
Lately I have been thinking about giving the first option a try, and titling my chapters. This would the benefit of further 'focusing' a chapter on a specific plot point or event or what-have-you, and the hope is that the rest of the book would benefit from that focus. Plus, it allows me to think up interesting and evocative chapter titles. On the downside, thinking up lots of chapter titles would basically be like having to pick anywhere from twenty to forty titles for a single book, and I go through enough mental anguish just settling on one.
The very finest example I have seen of the chapters-with-titles tactic comes from Stephen Brust, in The Phoenix Guards. I will never forget one particular chapter, the title of which made me laugh my ass off even before I began to read: "In Which the Plot, Behaving In Much the Same Manner As a Soup to Which Cornstarch Has Been Added, Begins, at Last, To Thicken." (paraphrased, somewhat, as I do not have the book right here with me).
The third option is less one of style, I think, and more of efficiency. George Martin beings the chapters in A Song of Ice and Fire by identifying the POV character for that chapter (though he has begun to give them more artful sobriquets than their actual names). This has the advantage of pulling the reader immediately to the memories of whats been happening recently with that character, and also eliminates the possibility of actual confusion - a very real benefit in epic narratives.
While I do not actively label the POV character at the outset of my chapters in Twixt Heaven and Hell, I do make sure to nix confusion by being very up-front about who the scene is centered on (except in rare cases when I want that to be a mystery).
A year ago or so, while working on some ideas for future novels, I came up with a slight variation to POV Labeling that I cannot wait to use. Sadly, the novels I thought it up for are awhile out in my project list,yet... the idea is that instead of simply announcing the POV, I will include some quote or other snippet that not only tells the reader who they are 'with' in that chapter, but also helps to inform the POV character themselves. If the character is a bard, then I might begin their chapters with a couplet or short verse. One character (who already exists in the notes for the novel) is a judge, and his chapters might begin with quotes concerning law and morality.
I think the device has premise, but much like thinking up new titles for each chapter it could get stressful. Setting apart a sentence or two like that means it really needs to shine.
I might have mentioned something about chapters that are divvied up
entirely by length, but I can't recall any book where I've noticed this
happening. I feel that most authors key their chapters to general events
in the storyline and make them as long as they need to be. The above differences fall to style, but will still be guided by the relation between chapter and plot.