This does not mean that the knowledge, skills and processes described should always be applied uniformly on all projects. The project manager, in collaboration with the project team, is always responsible for determining what processes are appropriate, and the appropriate degree of rigor for each process, for any given project.

PMBOK的一段话告诉我们在应用已有的知识的时候要考虑知识的适用条件，项目管理知识的精髓在于选择和裁减。