How does a writer use dialogue? (Mainly prose)
They change from description into dialogue in order to shift the focus from scene-setting to the characters
How it looks on the page?
Paragraph positioning may be important in changing the focus, because it is a smoother way of transitioning between two ideas.
Flow?
The writer might move points along quickly to make the description seem like a journey and to keep the reader on their toes and expectant.
Attention?
Snap from general description into a zoom/focus point, emphasis on the importance of the zoom