Every chapter or vignette or scene must have its own arc and its own beginning middle and end. Its own climax.
My book is told in vignettes, and I have two narrators. It switches from one narrator to the other. They get about 2-7 pages each time.
Sometimes I get confused on what the climax is for every scene. It always comes back to this: what is the main point? Before I write a vignette, I ask myself, What are we learning in this scene? What is the question that is being answered? For example (not related to my book) a boy tells a girl he loves her and we want to know her reaction. So the question is, what is her reaction? The answer to the question should come near the end. It should be the climax. The rest of the scene should lead up to it. Once the question is answered, another question should form.
Like, what is he going to do about it? How are they are going to resolve their differences? Whatever the question, it should be more exciting and interesting than the question before it, but not as exciting or interesting as the question it leads to. This keeps a nice pace.
Every time something gets revealed, something else comes up. You never want your reader to loose interest. Nor do you want to give them too many questions and no answers. (Ahem...like the TV show Lost).
This also ensures that the climax of your book is the most interesting part. The book's climax answers the book's biggest question and changes the main character's life.