We use styles to format text, and not direct formatting (i.e., we do not use the tools in the toolbar). Styles allow readers to change how the italics or bold text is displayed if they have difficulty reading it; for example, if bold letters are too thick. If direct formatting is used, readers can't change the content in a way that works for them (they are unable to load their own style set).
There are few exceptions to this rule. We use direct formatting for:
Q: Can direct formatting be used for alignment purposes? For example, we use an asterism as a decorative break. Should we simply hit the button in the Home Row for centre alignment? Or should we make a new style, based on Normal, that has centred text? For a second example, a book had a number of block quotes, and some of these quotes were centred while others were more left aligned. Should we make a new style for the centred quotes? To add to this a bit, can direct formatting be used in any capacity at all? (Of course, not for bold, italic, or underline). Thanks!
A: The cardinal rule: we almost never use direct formatting. We don't need to center the asterisks.