This seems obvious, but it isn't always as obvious as we believe.
In order to get good at something, we have to practice it. This is a fundamental concept when you look at study and learning skills in anything.
I was always a very practical learner, I learnt things by doing them. I got good at math, computers, (and martial arts :))... things where you did things and solved problems. I had a harder time in subjects that required more memorization. Names, dates, terminology... those tests didn't go as well.
After school and getting involved in teaching, both in Martial arts and post secondary, I think I figured out why. I didn't study for those right.
I could memorize things well enough, if they where things I was interested in. But when it came to studying things I wasn't interested in and had to memorize it didn't happen.
Anyways, the trouble is if you want to be able to remember things you have to practice remembering them. Seems simple, yet high school me re-read the same text over and forgot it all by the next day anyways.
This is why flash cards work really well in things where you have to remember information. They force you to practice recalling the information, which makes it easier to recall. Practicing reading the same information will make you better at reading it... but not always recalling it.
The same thing applies in the martial arts. If I want to teach you to get good at taking someone down that is resisting, I need to get you to practice doing so. Static drilling makes static drilling better, and that is important in developing technique. But to truly get good at something to where you can do it live, you have to practice doing it live.
This is also something that sometimes is lacking in martial arts schools. The goal becomes appearance rather then function, classes get run like military drill practices to keep things looking crisp and clean... Creativity and learning to do things live looks messy at times, it is something that comes out of chaos.
It's the difference between using a app that you scribble your finger in to paint a picture by filling in the area and it won't colour on the outside of the lines anyways vs freehand drawing.
Sometimes we need to colour within the lines, it's easier to get something that looks good that way. It teaches us a isolated aspect of the whole, and is a good way to learn about important concepts. But, in order to learn real skill and be able to freestyle we have to practice free styling, and sometimes it will look like scribbles. :D