For weeks, Kubrick pushed Duvall to the brink of sanity. Duvall was forced to cry so often and for such great lengths of time that she had to keep a water bottle nearby to stay hydrated. Her hair was falling out in clumps. Still, Kubrick didn't care—he made Duvall perform a record-setting 127 takes of the baseball bat scene. Duvall's co-star Jack Nicholson credited her with "the toughest job that any actor I've seen had, because forty percent of that movie, she's hysterical," but he believed that perhaps there was a method to Kubrick's madness.
"He beat Shelley into that performance," Nicholson said. "If that was me, I don't know what I would do. I do not. I still wonder. You're supposed to be able to do it, but for four months? But she did. She's brilliant in the movie."