never center the subject

Never center the subject. All the good photographic books tell you that. Unless of course you want to. This tree has so much staying power, that for me, I wanted it bang in the center of the frame. Static. Dominant. A very centered composition communicated that in a way that a perhaps more aesthetically pleasing offset arrangement doesn't, to my eye. Compositional rules and guidelines are great when you are starting out. But really, they are short summaries of deeper truths or ideas. I think you really need to take the time to understand the motivation behind those guidelines, so that you can make compositions say what you want them to say.

Behold the apples’ rounded worlds: juice-green of July rain, the black polestar of flowers, the rind mapped with its crimson stain. - Apples, Laurie Lee

I think of it in the same way that you learn grammar at school. The correct way to put sentences together, to provide meaning. Perfectly apt for a business letter or formal discussion. Not so great to really let you see and smell the apple. Visual language has many of those constructs and guides, that should be equally well thrown away when appropriate to the story. I think it is important to spend the time to learn the conventions and ideas in classical composition. But try to go beyond the how-to books that superficially list the ideas. Work out what these visual arrangements say. Work out what you want to say. Use what expresses your ideas most clearly.