no, it's actually very possible! gcse content for most subjects isn't that much, so as long as you remember a few key details and listen actively in class, you should be fine that said, I'm not saying don't revise if you think you need to
^^this definitely even for A Levels, as long as youre attentive and have a good memory and understanding of the content, revision isnt necessary for most subjects for some people. im not advocating for no revision, but it is possible for some people to have good grades without revising .