It's dialogue echos throughout the film. When the scene repeats, with each performance becoming more and more intense, it is electrifying. And while Cukor was definitely a studio director, who pulled the company line, he did try interesting things in the film. The most obvious of these is the use of mirrors in the film. Coleman often peers into his own reflection.
Mirrors pop up in almost every scene.
One even wiggles seductively when Winters first meets Coleman in her workplace. A mirror is something different for her. She sees herself in it no matter whether it is stable or not. And so do we. It has an excellent script that covers all the angels.