I first took the PSM I exam back in 2011 after taking the PSM course from Ken Schwaber. I had originally met Ken on a Scrum project back in 2000 and had been managing projects using Agile techniques and Scrum since that time. I took the class and immediately took the exam without studying or reviewing the Scrum Guide. I figured I had been practicing Agile for so long, I didn't need to study. Well, I learned my lesson. Needless to say, I didn't pass. I got an 82%. Good, but not good enough. A couple years later I decided to take it again. That time I created a personal study guide with questions and answers that I researched, and that is how the first iteration of this practice exam was born. You can still find those original 80 questions as part of my PMI-ACP Preparation Study Guide on Amazon. The version you are reading now has gone through 7 major revisions of both the PSM 1 and PSPO 1 practice exams as well as countless minor revisions. Each Scrum Guide release obviously calls for a new version, and every now and then I scour the blogs and Scrum.org community platform for insight into questions and possible answers. I have also taken the exam myself a number of times just to confirm my that my practice exam content and my training content is still aligned with the current exam questions. I am happy to say, I have not gotten less than a 94% score since that first time. There are always 2 or 3 questions that I either miss accidentally, or I probably disagree with. As you know, there is a some "interpretation" needed and even contradictions in the Scrum Guide and recommended reading, but all in all, the important parts of Scrum have remained consistent for 20 years