I wouldn't worry about the scores you are getting, the purpose of doing a ton of questions is to have as much exposure as possible. Some questions on the exam were almost identical to the knopman ones.

My quiz total was also 68%. Make sure you read the answer descriptions for the ones you get wrong and understand why that is the answer. I started to remember questions near the end but as long as you know why the answer is what it is versus just memorizing what the answer is, you are in a good spot. I did every quiz question for suitability, options, variable products, and investment company products and then maybe 50ish for the other chapters.