You need to go thru Destroyer a few times. Most of the high scorers went thru it at least 2-3 times. You'll probably see the results you're seeking during your second time around. Just try to learn the content on the first go-around without worry about how many right/wrong answers you score.
Yea i went through chads videos and his quizes and i still probably got around 50% right the first time through. Dont get discouraged about the destroyer books, they really do kick your butt the first time around but you will learn from it.