The only time I bothered with styles was when I was looking to create cohesive documentation for a large team, along with templates to help others create such documents.

Ironically, at the time the corporate templates didn’t even use styles. It was just a 5 page doc with all the different things a person might use, and we were expected to copy/paste what we wanted to get the proper formatting. This wasn’t officially stated, but that was the only way I could see to use it.