In most aspects, when you're 'writing' a story, you're using your own voice, your author's voice.
Yeah, there's some basics you should stick too, but you aren't writing an APA paper or what not, there's no need for such level of formality. 'Cause it'd hinders your author's voice in a lot of scenario.
Language changes overtime as well, nothing is permanent per se. There are moments when you may not know if you should do this or that, and you may look up what is correct and go with that, I think that's fine.
When you 'instinctively' wants to go with this instead of that though, I think in most scenarios you should go with this and if you change your mind later, you can change it to that.
Some audience may find your author's voice a struggle to get through cause of your 'grammar choice', others will find it lovely. No matter what you do in this writing world, someone gonna love you, others gonna not love you.
The whole reason for 'grammar' per se, is to increase the efficiency of communication and lower its chances of miscommunication. To me, it's at its most usefulness in formality type of writing, like science papers.
In creative writing, it's not much. We are authors at the end of the day, and each of us will have our own 'voice'. Sure, grammars has something to do with that, but I doubt we all speak in such tongue that's APA style. 'Cause it's just not necessary in casual conversations, or even literature writing in essence.
I'm not saying to dismiss grammar altogether, obviously, the basics is needed, to go with this instead of that when it is obvious. But like. Example. There are times when I should use 'nor', but I don't, cause it doesn't make the sentence as pretty as it would be with 'or'. I feel like the sentence would be more powerful with 'or', so I don't use 'nor', even though clearly, I should grammar wise.
Best way to say this is probably that saying, "Learn the rules, know the rules, then you can break them at your leisure."
Awespire is not a word, but I'm pretty sure one of my character would say that, so I was like. "Well, it's a word now."