There is a golden rule how to effectively learn data for an exam: “dropping items entirely from your revision … is wrong. You can stop studying them if you’ve learnt them, but you should keep testing what you’ve learnt if you want to remember them at the time of the final exam.”
Also: “cramming doesn’t work”: “Recall is supported by a network of … areas of the brain, including the frontal cortex and the temporal lobe, which coordinate to recreate a memory from the clues you give it. Just because your visual cortex is fluently processing your notes after five consecutive hours of you looking at them, doesn’t mean the rest of your brain is going to be able to reconstruct the memory of them when you really need it to.”
Read more in How we learn by Benedict Carey.