In a single book, changing writing styles is a poor idea, unless you're improving. Now, my writing style is without a doubt just dialogue. Scroll through Elemental Academy and take a shot for every quotation mark that appears. For humans, it is literally impossible to drink that much. Here, I'll give you an example.

*slams table with a rolled up newspaper*

Chapter Five of Elemental Academy! Only around FOUR one-line paragraphs aren't quotations. It's 1,000 words long!

But my bad. Some quotations are followed by actions. I'm not counting those, but still.

The point is, the more you use your best writing style, the better you'll get at it, and the better your writing will be.