Very Interesting question. I personally, have a rigid scheme of expressing my story and whenever I get an idea, I go ahead with it only if I can express it within that scheme. Besides, that the instinct is purely another word for taste, and as my taste evolves so does my choice for choosing subjects and structure, and all that.

"This is the time. This is the place. This is the vastness. Right here is paradise. Always. Always."
-Byron Katie

I get in the present moment to life around me. Sometimes the perfect piece of music puts me at a place that allows me the access of instincts.

Or I have some rituals that can assist my process. One is lacing up my boots just before I write. It triggers the primal side of me that says, it's time.

I would suggest finding something that is unique to you that triggers your primal instincts. Then write before you think. When you rewrite, then think.

Those are my thoughts. Hope it helps

Time and effort brings it. Sometimes you can't see your own skills developing. I recently consulted on a music video with a very involved story concept that was too expensive for the band. During the meeting, I figured out how to make the story make more sense and the video cheaper on the fly. I was able to solve the problem and do it quickly because I've spent so much time with stories.

When I used to train new script readers, I would give them some specific tips, examples, etc. But I would always say "Your innate sense of Suck vs. Not Suck is the best tool you have."

Plus, if you have good people to read your work, eventually the sorts of notes you get about your writing sink into the way you write.

Anyway, I'm still very near the bottom of the mountain, but I can already see how development of these things happens.

Best way to learn is to write about your favourite films in terms of writing. That way you understand how all the elements work and also it *informs* your own writing.