The Charts page demonstrates some of the many ways to use Custom Page User Items. I added a Custom Page User Item and then added multiple User Items to it including headings, text, and, of course, charts. Some of the charts are linked because they are configured as Page Items. Others are embedded on the page because they are configured as Content Items.
The recommended way to add charts to the site is to follow the method here: add a Custom Page User Item and then add chart User Items to it. You can keep it simple, if you want, by adding all the charts as Page Items.
The text above is in the Main Content field of the Custom Page User Item.