I think what people mean when they say to study efficiently and effectively is not to stuff your brain with information in one day, knowing all of your information but just going to forget it again after exams are finished isn't good for you in the long term because you will just have to relearn what you knew for your next exams
study over a long period of time (maybe every weekend revise all your notes and try to remember them) keep revising what you already know, adding to that knowledge with the new information you get from school
when you come up to exam time ask the teacher for practice exams to take and see what areas you need to work on more to improve....
but generally revise all your notes again, maybe get friends to quiz you.....but remember different people have different ways of studying and learning...some people learn through pictures, others through memorising notes and others by someone talking to them and telling them how to do something or the facts they need to remember....figure out what helps you learn the best and use that to help you study
