The spacing effect: why little and often beats cramming

Here is one of the most reliable findings in all of learning research, and one of the least intuitive. Take a fixed amount of study time and spend it all in one sitting, and you'll do fine on a test tomorrow. Take that same time and spread it across several shorter sessions, days apart, and you'll do worse tomorrow — but far, far better in a month.

This is the spacing effect, and the catch is right there in that trade-off. Spacing feels harder. Each time you come back you've forgotten a little, so you have to work to recover it, and that effort reads as failure even though it's the very thing building durable memory. Cramming feels great and fades fast; spacing feels rough and lasts.