Understanding Layouts in Phoenix Framework

The user pico303 is confused about the layout system in Phoenix, specifically the reason for having both root_layout and app.html.heex. They seek to understand why both these layouts contain menu items by default and question the default assignment of app.html.heex for LiveView pages. pico303 is curious whether it is common practice to customize layouts based on user authentication status and whether different layouts are used for public, login, and authenticated views, or if conditional rendering within a single layout is sufficient.