I would tend to agree about reading the book in a more targeted approach. It definitely helped me as I got deeper into my exam prep.
I prepared in a similar way, but I did still read each chapter as I prepared to test on it. My approach was the following, (and it lead to me passing the exam my first time)
•Start a unit in PMBOK.
•Take a quiz on PrepCast that covers the Unit to understand my baseline of knowledge
•read the chapter
•retake quiz
•Review incorrect answers on PrepCast and read the passages that are recommended during test review
•retake quiz
Rinse and repeat until I feel comfortable on the subject material.
This helped me be focused on my study, but I still found major benefits in reading the material as I reached the topics at hand. As opposed to, reading the entirety of the PMBOK 6th edition and THEN studying after.
Cornelius Fichtner, PMP, recommends a smarter PMP exam prep approach, advising candidates to focus on the Exam Content Outline, take a course aligned with it, and practice with an exam simulator. He suggests using the PMBOK Guide and other guides only for specific clarification, saving time and improving exam performance.
Training for Project Management Professional (PMP)®, PMI Agile Certified Practitioner (PMI-ACP)®, and Certified Associate in Project Management (CAPM)®