I wanted to follow up on this and see what others thought. I came here with the same question.
At the beginning of each chapter, the MERM has a "NCEES Exam Specification and Related Content" section, which lists the sections of that chapter that are specific to each discipline of the Mechanical PE exam. Further, the PPI2Pass study plan states, "the NCEES Exam Specification and Related Content section at the start of the chapters will guide you on which sections are specific to your exam. Other sections and chapters are supportive to the knowledge area on your exam."
If it was important to study the entire chapter, then why have this language in the study plan? What does it mean for topics to be "supportive to the knowledge area?" I just want to make sure I'm making the best use of my time while also not missing any important topics. Any other input would be appreciated.