I think understanding the concept of style is important. However, perhaps more important is understanding how to use it and what it really looks like in writing. The key to this is to read, and read a lot. Of course, this is recommended for writers anyway; it’s a solid strategy for understanding and improving all areas of your writing. But I think it especially applies with writing. I often help friends and family members with their writing, whether it’s editing their work or helping them figure out what they’re supposed to be doing. With time, I’ve come to understand their different writing styles. I know that my twin sister uses more emotional language in her work, and my older sister’s writing is much more bare and direct. Knowing how people around me write helps me see the differences in my own style.
That doesn’t mean you have to go out and study the writing styles of all your friends. I think it’s just as helpful, if not more so, to study famous writers and their distinct writing styles. Many of these writers could be recognized for their style alone. I found an article that discusses a few famous authors and does some analysis. It also gives some useful advice for developing your own writing style, so that’s a nice bonus.