is this how the brain/memory works?

so im revising for some pretty big exams soon, and i want to keep lots of information in my memory. in order to do so, anytime there is something else that i would remember usually, like the date of an event or some slightly important information, i make a point not to remember it. my logic is, that instead of wasting my memory and energy on that i save it for the info for my exam. but not remembering these things is coming back to bite me and i dont know if i should keep it up if thats not actually how the brain works. so, if anyone knows, i would love to hear how this actually works. thanks