Pick two, sometimes expressed as pick any two, is the principle that in many sets of three desirable qualities, those qualities will be somewhat mutually exclusive.
One of the classic “pick two” scenarios is the triple constraint of project management and product development, which consists of these elements: schedule, scope and cost. Each constraint defines a boundary of the project and none can be altered without affecting at least one of the others. For example, if a software product must be developed quickly, it will probably be necessary to cut back on features or increase development resources.
The Venn diagram above illustrates the pick two concept. Clients typically want products or projects to be delivered quickly and cheaply but also to be of high-quality. The areas of overlap between in the diagram indicate the combinations that are likely to be possible. The product can be: great and cheap -- but not fast; fast and cheap -- but not great, great and fast -- but not cheap. The client is advised to pick two: Decide which two of the three requirements are most important and be a little more flexible with the third one.