Thanks to commenter Shelly Keith Childs for providing the following George Lucas quote:
“Lots of times actors have very good instincts. They’re thinking about the character a lot more than you are. You’re looking at the whole thing, they are looking at that particular person. If they’re uncomfortable or something doesn’t work, it’s usually because there is something wrong with it.” ~ George Lucas in ‘The Making of Star Wars’ by J.W. Rinzler.