CMMI exists in two representations: staged and continuous. The staged representation provides a standard sequence of improvements, and can serve as a basis for comparing the maturity of different projects and organizations. The continuous representation allows the organization to focus on the specific processes that are considered crucial for the organization's immediate business goals.
Regardless of which model an organization chooses, all CMMI best practices should specifically be implemented for each individual organization according to its own situation and operational environment.
Because the CMMI-model is a guideline, it is possible to implement only the Best Practices which are relevant for your organization.