I wrote my first feature length screenplay in the mid 1990s after reading the screenplay for Don't Look Now (I'd already seen the film). I read the Daphne Du Maurier original some years later.
Anyway, my first screenplay was rubbish. A silly Minority Report variant. But my second screenplay, a ghost story, showed a lot more promise, and foreshadowed my later gothic novels. Robert McKee's Story continued to propel me along the screenplay road, until I made the move to novels/short stories in 2004. This happened when I realised screenplays just weren't cutting it for me. I wanted completed works, not templates.
At that point I bludgeoned ahead with three novels, none of which will ever see the light of day, for good reason. At the same time, I read a lot more books on writing to help hone my craft (including The First Five Pages by Noah Lukeman). I continue to learn, and consider myself a lifelong student of learning to write better.