In school, you don't learn something and then move on -- you learn, review, and move on. If you skip the review, you're not likely to remember, or use what you learned. The way I see it is, our minds are storage places. When you come across new information, it is randomly tossed into the mindspace. By analysing, you take this knowledge and reshape it into a configuration that fits best in your particular mindspace. Only then can you use it to its fullest potential. It can still be used in its original shape, but it cannot be easily built upon.
Another way of putting it is to say that when someone gives you knowledge, it is their knowledge, designed to fit into their mindspace (unless it is regurgitated; then you have no idea whose mindspace it fits, which is a little scary if you think about it!). It only becomes yours when you break it down and reshape it to fit in YOUR mindspace. People can tell me all day long that drinking water is good for me, but it remains their knowledge until I reshape it into mine (in this example, by experiencing the difference between good and poor hydration). Because of this way of thinking, I never take anyone's words to be truth for me -- they may be verrrrrry similar but they will have slight differences that will create instability in my thoughts if I do not first reshape them to fit my mindspace. There's only one side of difference between a rectangle and a pentagon, but they don't fit together in a pattern very easily.