You learn grammar so you can break the rules with purpose and intent, but boy howdy you should break those rules. Every novelist should have that failed novel where they tried to go Full Joyce and break all the rules—and yes, that novel will be failed, but what fun. And if it isn’t a Fail, you certainly don’t need this blog or my grimy thoughts.
I’ve always had the vaguest and most primitive grasp of grammar, because I’m a lazy man who relies on instinct instead of book-learnin’ as a rule. Writing has always come easily for me, and I’ve always regarded grammar as a collection of loose guidelines instead of, you know, rules. When you show a novel or story around to enough people, someone will note your grammarly failings—the dubious overuse of commas, perhaps, or the clear evidence you don’t really know how to use the semi-colon (the most mysterious of the colons). And humorless people will correct your grammar, no doubt.
Going Full Cormac
Look, no one’s telling you that you can pull off a Full Cormac McCarthy and just ignore whole swaths of our delicate, glorious language; not many people can go Full Cormac (and some would argue not even Cormac himself is pulling it off) without falling off a cliff into incomprehensibility. But you shouldn’t feel like you’re a prisoner of grammar rules handed out in school. Use those commas freely. Abuse verb tense, write glorious, overlong run-on sentences.
Just do it with purpose. That’s the key. If your grammar is muddled because your grasp of it is muddled, then all the grammar bluenoses have a point, kid. If you’re doing it on purpose and you like the effect, then ignore all of them and don’t ever look back.