And how about Lucas who was always in the editing room to help it get cut?
He was described by James Cameron "George is an editor, he thinks in cuts." during that tribute that Vintage and I were talking about in the other thread.
I know that Kershner and Marquand were responsible with some of the acting choices and so-on, but I think some scenes probably looked the way that they did because Lucas told Kershner and Marquand how he wanted them to play out when he told them the story. (which we all know he wrote)