Since customer needs come in all shapes and sizes, variety is a fact of life in any service business.
The Law of Requisite Variety, also known as Ashby’s Law, for the neuroscientist who first formulated it, says that any control system must be capable of a number of possible states that is greater than or equal to the number of states in the system to be controlled.
In other words, if there is variety in the environment you need enough variety in your system to absorb it effectively. Think of a juggler: no matter how skilled the juggler, there will always be a point where there are too many possible states for the juggler’s mind and hands to maintain control.
There are two ways to deal with variety. You can reduce variety by standardizing inputs and controlling the environment as much as possible, or you can design a system that’s capable of absorbing more variety.