A gas supply system for providing a plurality of process gases to a process chamber includes a plurality of mass flow controllers each arranged to receive a respective subset of the plurality of process gases. Each of the respective subsets includes more than one of the process gases, and at least one of the process gases is provided to more than one of the plurality of mass flow controllers. Respective valves are arranged upstream of each of the plurality of mass flow controllers to selectively provide the respective subsets to the mass flow controllers. A first quantity of the plurality of mass flow controllers is less than a total number of the plurality of process gases to be supplied to the process chamber. The first quantity is equal to a maximum number of the plurality of process gases to be used in the process chamber at any one time.