I upvoted but I was not taught this! I have had to slowly figure it out on my own. Writing things down is kind of like augmenting your brain. It's a memory that does not forget. When working through a problem, writing it down tends to point out the holes in your understanding. A corner case is never lost or forgotten when written down, it just stares at you until you write down a solution. The next step after realizing this is to develop the discipline to write things down and to organize your environment so it's effortless to write things down.