There is a myth not to practice

I came across a person who asked me not to opt for any practice resource and just study the syllabus twice or thrice which would be enough to clear the GFACT certification exam. But i was adamant that i will first practice on the GIAC Foundational Cybersecurity Technologies mock tests and only then will give the final attempt. His strategy failed. He did pass but did not score a good one like i did. My score in the final is 80% and that is way too above than just passing the certification exam.