When they started the 170 program years ago the answer to everything was basically system logic. That has changed over the years to where they do actually expect you to have knowledge of how all the systems work. I think you only need 80% systems knowledge to pass so you don’t have to be perfect. But please don’t show up without 100% knowledge of limitations and memory items. And don’t go to simulator without complete memorization of profiles and callouts. You will get destroyed.