Before software, the schedule was furniture: a wooden board hung in the production office, holding one thin cardboard strip per scene, color-coded for day or night, interior or exterior. Scheduling meant sliding strips around by hand until the shoot made sense: group the same location, bunch an actor's days together, chase the light. The genius is that it makes the expensive things visible: moving a strip is free; moving a company to a location twice is not. A century later the board won: every scheduling tool on earth is still strips. Mine just move themselves when you ask, and warn you when a move costs money.