You retain the material by constantly reviewing it. My coach taught me about what is meant by “rote memory”. If you ask any teenager who grew up in church what John 3:16 is, most can say it right away. In fact, even though I’ve been through two quiz years on John in NIV, I can still do it, without thought, in KJV. This is because I said it so many times as a young kid that it’s permanently in my mind. That’s the way you want the quiz material to be stored in your memory. Not only will this help you with your quizzing, but it also ensures that the Word will always stay with you.
The basic rule of thumb for retaining material is to quote everything you know, to someone else, at least once a week. As competition nears, you should probably step that up. Teams preparing for nationals will probably be quoting the entire material every day, on top of reviewing analysis and concordance. Think of it this way. You work hard to store the material in your memory and when a question comes up that tests your knowledge, you want to be able to earn the points. The longer it’s been since you reviewed it, the more likely you will miss a question that you could’ve answered at one time.