Why is there so much precasting?

This might help?WHO'S WHO IN THEATREProducer:Leaps Tall Buildings In A Single BoundIs More Powerful Than A steam LocomotiveIs Faster Than A Speeding BulletWalks On WaterGives Policy From GodDirector:Leaps Short Buildings In A Single BoundIs More Powerful Than A Electric TrainIs Just As Fast As A Speeding BulletWalks On Water If The Sea Is Calmspeaks on behalf of GodPlaywright:Leaps Short Buildings With A Running Startbelieves he is Thomas the Tank EngineIs Faster Than A Speeding dummySwims WellIs Occasionally Addressed By GodActor:Makes High Marks On The Wall When Trying To Leap BuildingsIs Run Over By Trolley Buses and all would be Tank EnginesCan sometimes Handle A Prop Gun Without Inflicting InjuryDog Paddles wellTalks And Listens To Trees As Though It Were GODTechnicians:Runs Into BuildingsRecognizes Locomotives Two Out Of Three TimesIs Not Issued AmmunitionCan Stay Afloat With A Life PreserverListens To Inanimate Objects And Talks To WallsElectrician:Ruins buildings with a single switchOnly allowed an electric train setUsually goes up in smokeKnown to aviod waterHearing is colour blind and only listens to the lightChorus:Falls Over Doorsteps When Trying To Enter BuildingsSays, "Look At The Choo-Choo!"Wets Self And Blames The Prop Water PistolCan only play In Mud Puddles wearing floatiesMumbles To SelfStage Manager:Lifts Buildings And Walks Under ThemKicks All Locomotives Off The TrackCatches Speeding Bullets In Teeth And Eats ThemFreezes Water With A Single GlanceIs GOD !!!!!!!!!Joe