In a long New Yorker profile on writer/director Tony Gilroy, the film-maker emphasizes the importance of reversals--basically, surprises, in screenplays these days.
As the profile writer, D. T. Max notes, "Gilroy believes that the writer and the moviegoing public are engaged in a cognitive arms race. As the audience grows savvier, the screenwriter has to invent new reversals--madder music and stronger wine."
Gilroy pushed this idea to the limit in "Duplicity." It features the same line of dialogue five times, each time with a reversal that suggests a different way to interpret it. There were also elements of it in his very much more successful Jason Bourne scripts (although if you read the article, you'll find out why he hated the resulting movies). He also wrote and directed "Michael Clayton."
Gilroy also believes in strong pacing. Steven Schiff notes that Gilroy writes in spurts. “Dolores Claiborne” and “Duplicity” were each written in about twelve weeks. “He feels fucked up and blocked and crazy for a long time,” Schiff says. “He tortures himself. Then, as it’s coalescing, he sits down to outline, and when he’s outlining he insists on doing it very, very fast — the whole movie he sketches out in, like, four days. I’m sure that during those four days his wife doesn’t see him and no one talks to him. And the reason he does that, he says, is it’s a movie and it has to move fast. ‘I have to write fast. I have to think fast. My fingers have to move fast.’ ”
(Want to write a movie yourself? There's useful information in my book, "Your Writing Coach" and in "Top Secrets: Screenwriting," both available from Amazon and other online and offline retailers.)