If I'm in theatre, cinema doesn't even cross my mind. Similarly when I'm making a film, theatre doesn't cross my mind.
I put everything I can into the mulberry of my mind and hope that it is going to ferment and make a decent wine. How that process happens, I'm sorry to tell you I can't describe.
You collect as much information as you can and then you put it into the mulberry of your mind and hope that you come up with a decent wine. Sometimes you do; sometimes you don't.