I'm not going to sugarcoat it — I failed the HAZMAT endorsement test twice before I finally passed last month. The first time I walked in completely unprepared, figured it couldn't be that different from the regular CDL knowledge test. Wrong. The second time I studied but used some random free app that had outdated questions. Third time, I actually buckled down and found a solid HAZMAT practice test that matched the real format, and that made all the difference.
What tripped me up early on was the placard requirements and the table sections — specifically knowing which materials fall under which hazard classes and when you're required to display placards based on weight thresholds. The study guide I used the third time broke those tables down into digestible chunks instead of just making me memorize the whole chart cold.
For anyone just starting out: give yourself at least 2 weeks, don't skip the segregation rules, and drill the placarding thresholds until they're second nature. Curious if anyone else found specific topics harder than others?