Perhaps more than any profession, writers are infamous for their quirky and possibly counterproductive on the-job habits. In his heyday, screenwriter Paul Schrader would write exclusively at night, often until five or six in the morning. He fueled this with a lot of alcohol, nicotine, and cocaine (the latter a habit shared by many of his actors). While working on “Taxi Driver,” he would stuff a pistol under his pillow when he eventually did go to sleep. At other times, he’d keep a loaded one on his desk.But of course,…