Quick design sketches in preproduction give the Art Department a running start on building production assets. There is never enough time, never enough resources and never enough man power.
In television these simple drawings inspire departments towards a goal and are used as a collaboration tool with the Production Designer and Showrunners.
This approach not only saves money and time but allows for a greater degree of execution as valuable resources are not wasted in searching and testing ideas and options. In other words, it’s easier to hit a target when it’s drawn for you.