Anybody that tell's you they didn't find nav a little much at the beginning is full of c**p so calm down we have all been where you are now . personally i would not get hung up about the charts because little or no questions in the exams and the ones the do know are basic feedback questions that you will reckonise .
Your two weeks in brush up course will relieve any worries you have , don't look into those progress tests too much ..topgun.