What principle of joint operations entails expending minimum essential combat power on secondary efforts in order to allocate the maximum possoble combat power on primary efforts?

The principle of  joint operations that entails expending minimum essential combat power on secondary efforts in order to allocate the maximum possible combat power on primary efforts is called the economy of force. It is one of the principles of war that is based on Clausewitz's approach.  The economy of force is the principle where we employ all of the available combat power in a way that is the most effective as much as possible, attempting to allocate a least amount of important combat power to any efforts. It is closely associated to the idea of force concentration. According to this principle, any part of the whole effort should not be left idle.

10 neutrons is the answer