Yes you are correct with the listen to what they tell you. The Harley lady that was in ours failed because of that reason. She acted like she knew everything and bombed everything... her son passed though. I still think if you learn the basics of shifting and moving it will still help you be more confident while in the class though. This one lady was freaking out about friction zone the whole class... the other lady who wound up leaving couldn't get the bike to move. It would of just flowed a lot easier if people at least had basic operating experience imo. Some catch on faster than others. But with knowing basics you're less likely to be worried about it along with everything else. The only experience I had was when I got my s50 about 25-30 days prior to the course. The instructors told me to stop showing off while doing the weave/ swerving practice because they could only do it using friction zone, and I did it using nothing but the throttle. Having a smaller bike personally though helped me with that and with dodging all the potholes in our lovely state haha.
This hasn't been the case in my experience. Roughly half the people in my class were complete newbies and most of them passed the class. Most of the people who failed the class had riding experience.
I think better advice would be: Listen to and follow your course instructor's advice and you will do fine.