If creating internal navigation within a sub-section of the page, headline block should always be used.
It is now possible to create hierarchies with Long product pages. This means that the editor could use product pages as navigation. The editor should still avoid creating hierachies of more than three levels.
Could be used for any type of content, both text and graphics. If you have need for a banner at the top, use the Content background image. Avoid staggering several One column-elements at the top of each other, unless there is a reason for it.
Use it to easily create two columns of content.