Whether you use Google Docs, Libre Office Writer, Abi Word, Microsoft Word, Apple Pages …. whatever it is, you can save so much time (not to mention your sanity) if you use preset styles.
Lets assume for example that you want every heading to be red. The long way of doing this is to select every heading then select red. Instead if you use the preset styles this process becomes a lot easier and faster if you can just specify the colour you want to use once and then have that change apply to every heading.
One of the little known things about the preset styles you see for headings, paragraphs is that they can look any way you want within reason and you don’t to individually style every one as you go along. As you might have experienced, what you think might good initially can be something you later change your mind about.
My opinion is that styling the way your text looks it too much of a distraction from the content you are writing. Good writing doesn’t come from picking colours or fonts, it comes from words. So focus on getting those words written while using appropriate preset styles (headings for heading text, paragraphs for paragraph text), then leave sexing up the presentation of your document until last. You will save yourself so much time and get more done faster.