Shop drawings represent an elementary form of delegated design. The process involves contractors and suppliers who design the components for which they are responsible. If the project architect of a building had to design every single connection and interaction between systems and components, it would be an arduous process.
Most architects do not have the skills to design to that level of detail and that would cause delays and frequent defects in design. Using shop drawings provide the contractor and the architect with an opportunity to review what the subcontractor or supplier intends to supply or construct before approving the fabrication or construction