Rules are meant to be broken
I am not naturally a rule follower (which is why I would be unlikely to darken the doorstep of a photography club) and while I can see the benefit of some of the rules in photography some of them are a little boring (and possibly a little old).
It is still a good rule not to ‘cut off the top of someone’s head’ in portrait photography, nor to have someone out of focus in a shot; yet, one of my favourite photos is one I took recently of a friend. We were laughing and having a bit of a joke and I was setting up for a portrait, the resulting candid (and out of focus) shot captures the moment brilliantly. A perfectly composed and focused shot would have been clinical and not true to the moment. I prefer truth over rules any day.
Breaking rules does offend some people and I think one of the reasons why is that the rules are, traditionally, well-understood and logical; having the horizon, horizontal is something that is less confrontational than an angled horizon. I am a bit of a stickler about my horizons but recently I saw a painting where the horizon was, challengingly, on an angle. I remember the painting well and went back to look at it several times. It made me stop. It made me think. And, after all, isn’t that the purpose of art or photography?
What rules are non-negotiable for you?