You might rarely need to use source ordering, but when you do, it is super handy, especially for SEO or other optimizations you want to perform for a certain screen size. Another example is when you want to show a sidebar on the left of the screen for medium and large screens, but on a small screen, you want that same navigation bar to be under your main content area. So, you will use source ordering to render the same code but display it differently on different screen sizes. This might not be the best design choice; you are likely to put your side menu on a small screen, in a drop-down menu, or a slide out menu, which appears at the left or the right of the screen. However, this is a simple example.
Source ordering can be really useful if you have a side navigation bar and some calls to actions in your sidebar. This is fine on large and medium screens, but what if you want to move the navigation elements into a drop-down or slide-out menu on...