Some people have the mistaken idea that their memory is like a mental muscle.
They think that the more they exercise it by memorizing things, the better able they will be to memorize new things. Thus, they spend a lot of time memorizing useless material in hopes that it will make them better to recall necessary things. Unfortunately, the analogy between muscles and memory is false. Muscles are indeed strengthened by spending time lifting weights. But the ability to memorize is not best developed simply by spending time lifting facts from pages.