Chapter Titles: Are Chapter Names Mandatory?
The "mandatory" first rule of writing is that everything is as mandatory as it is optional. Writers learn the rules so they can break the rules. Writers keep to traditions because they can further them in untraditional ways. Whether debating whether to write a prologue or rely on a character discovering a documented past, there are no "correct answers." The same applies to titling chapters versus leaving them numbered. Nowadays there are factors that will end up answering this question for any writer. Below is a comparative list of why chapter titles are and are not used.
The list above offers the most common responses I've heard when this topic comes up. Every book ever written provides its own style. Every author will give their opinion of craft based on their individualized experience. Many writers have also left the use of chapter titles to circumstance. It depends on the story itself, so let that decide.
Some writers will also title chapters pre-publication for the sake of organization. Once the editing phase gets wrapped up those chapter "labels" get backspaced and numbers reign. Others title their chapters after editing, tabling this "consistency concern" for later. The reasoning behind titling or not titling chapters are back-and-forth from writer to writer. Which ever one decides, the only wy to know is to try it for yourself.