A lot of shooters are fond of quoting the rules: both the (supposed) hard 'n fast rules and the not so hard 'n fast rules. As a rule, the rules for rules aren't any more hard 'n fast than the rules themselves. They are soft and unfixed... perhaps "subjective" is a better way to describe them?
Don't get me wrong, I think rules are helpful, often appropriate, and important! Maybe not all rules but certainly photography's rules. (As for other rules, well, I've always been, to varying degrees, somewhat outlaw-ish. Probably no surprise there.)
While rules -- hard, fast, or otherwise -- aren't generally intended to be rigidly followed, certainly not to the letter, they do provide a foundation for any shooter's understanding of photography, i.e., what works and what doesn't work. After all, if you don't know what works, how are you going to know if what (often) doesn't work suddenly works? If it works, that is, in a given instance as a unique approach to a specific image. (If that makes sense.)
I do have some favorite rules. They tend to be amongst the more common, simple and basic rules. (The Rule of Thirds comes immediately to mind.) While I don't always religiously apply the rules or use them in hard 'n fast ways, I do often use them in my photography; sometimes obviously, other times subtly. (Sometimes, in ways that aren't much more than barely perceptible "nods" to an established rule.)
Unfortunately, there are no rules for deciding when to apply the rules. (Or rules for deciding to purposely break rules or for ignoring them.)
The lack of rules for applying rules is sometimes a confounding thing for photographers. Many photographers, especially new-ish photographers, are grateful and enthusiastic being told exactly how to do things, photography-wise. That includes applying rules! That's why so many "How To" books and other learning media are so popular. And it makes sense.
Many books and learning and training programs, like knowing the rules themselves, are necessary for growing and expanding one's skill, efficiency, and quality of craft. Understanding and applying the rules, as well as learning exactly how to do so many other things, is often discovered when they're laid out for us, step-by-step. That's a helluva lot easier than blindly searching for that "how to" knowledge or hoping you accidentally stumble upon it. All this kind of stuff is very important to becoming all you can be as a photographer... unless you're some kind of photo-prodigy, which most of us ain't.
There is one rule, however, that's always hard 'n fast: With photography, the learning never stops. I don't care how experienced or successful a photographer might be, there's always more for them to learn, whether they believe that or not.
Personally, I think the never-ending learning process is one of the things that makes photography so cool! Doing so, continuing the learning process that is, keeps your photography fresh, vibrant, and exciting. Learning inspires! Learning is a muse! Course, so are things like beautiful, naked chicks in front of your camera but that's not the subject of my babbling today.
Speaking of beautiful, naked, chicks, the model at the top (who mostly fits that criteria) is Layla, snapped a few months ago.