Tolerance

One important concept in engineering is the idea of tolerance. According to Wikipedia:

Tolerance in engineering is the permissible limit of variation in a dimension or value of a parameter of a manufactured object. Dimensions and parameters may vary within certain limits without significantly affecting functioning of equipment; tolerances are specified to allow leeway for imperfections in manufacturing parts and components without compromising performance...

It is good engineering practice to specify the largest possible tolerance while maintaining proper functionality. Closer or tighter tolerances are more difficult, and hence costly, to achieve. Conversely, larger or looser tolerances may significantly affect the operation of the device.

Probably applies to societies, too...