Directors must be aware of the many aspects of this principle. If an establishing shot depicts two actors facing each other, Alice looking right and Bob looking left, then the close-ups that cut properly with the wider shot must preserve the look directions. Oh, and actors never look at the camera. Beyond the rulemaking is a set of overall guiding principles. Show, don't tell.
Expository dialogue is weak, imagery is stronger.
Behavior is strongest of all. Movie characters may range the globe in an epic that lasts weeks or months, but they rarely changes clothes. Their personal hygiene is rarely examined. Movies possess such inherent momentary detail that audiences confabulate vague connective tissue to round out whatever tale is being told. This kind of participation is one of the pleasures of movie-going.