I'm not going to sugarcoat it: I failed the MMC exam twice before I finally passed last month, and I want to be honest about what went wrong and what actually helped. My first attempt I went in way too confident — I'd been doing electrical work for six years and figured the practical experience would carry me. It didn't. The code theory sections absolutely wrecked me.
Second time I bought a study guide from a bookshop and read it cover to cover. Still failed, but closer. What finally made the difference was grinding through an MMC practice test every single day for three weeks. Not just doing them, but reviewing every single wrong answer and understanding the why behind it. Especially transformer calculations and load calculations — those showed up way more than I expected.
My exam tips for anyone starting out: don't skip the NEC code sections even if they feel boring, and time yourself on practice questions from day one. I was running out of time on the actual exam until I forced myself to work faster in practice. Happy to answer questions about specific topics if anyone's stuck.