sirius could pass any exam without studying bc he secretely liked the class materials and loved to learn
james pretended he didnt need to study but did it in secret bc he didnt want to ruin his carefree aesthetic
peter needed to work but he never knew how to do it so he begged the other ones to help, but he also really liked to learn about what he liked
remus didnt really need to study to pass but he still did bc he needed the best grades to have a tiny chance to get a job after hogwarts