Directors spend plenty of time preparing lighting setups and diagrams with their cinematographers before movies are actually shot. They take into consideration that they must hire extra help on set, known as grips, to carry and set up large lighting equipment. The time that grips must take to set up lighting equipment is factored into the shooting schedule to keep everything running on time.
Movie lighting can be used to create daytime scenes at night as well as nighttime scenes in the day. Shoots that run over could potentially ruin a director's film. Movie lighting helps directors stay within the budget because they can take a location when it is available night or day if need be.
Movie lighting for the most part is used to emulate natural lighting or real lights that people typically see. So, correct film lighting should barely be noticed by the audience. They key here is to be subtle and to provide better lighting on the actors and to make it appear as though it is coming from a visible light source.