Working memory
Working memory is the small mental scratchpad that holds what you are thinking about right now. It only fits a few things at once, and it clears out fast, so big piles of new information overflow it before you can really use them.
Think of working memory as your brain's desk. You can lay out a few things on it and work with them. But the desk is tiny. Try to cram a whole chapter onto it at once and stuff falls off the edges before any of it sticks.
This is why studying in one giant blur does not work. Your working memory gets full, the new facts push out the old ones, and nothing makes it into long-term memory. Breaking the material into small chunks keeps the load light, so each piece has room to settle before you move on.
So the trick is not to push harder. It is to push less at a time. Small groups, one idea before the next, short focused rounds. That is working with your brain instead of against it.
Maya tried to memorize 30 anatomy terms in one sitting and kept blanking. She split them into groups of 5 and learned one group at a time. Same terms, but now they actually stuck, because she stopped overloading her working memory.