You're close to mastering fast 터치 타이핑. This lesson is about ring fingers. It is not far for non-visual writing lessons, which are rewriting strings that rely on typing the same keyboard keys repeatedly.
Now think about what you can personally gai thanks to mastering 터치 타이핑. The first benefit of typing faster, which seems the most obvious, is saving time. You don't waste time looking at the keyboard, then the screen and then again at the keyboard. You make fewer errors when writing. It doesn't seem like a big issue if when typing you are looking at the keys, but if you think you are looking at the keyboard first, looking for the key, then looking at the monitor screen to see if you have made an error, you will realize that this is a lot of time. It's up to a lot of time compared to typing technique that AgileFingers teaches you. If you type without looking at the keyboard, your eyes are focused on the computer screen.
The time wasted on incorrect typing is a time that is very inefficiently used, because you focus your mind with the very act of typing. When you type without looking at the keyboard, you focus on the content of the text. The very act of typing is done unknowingly.
Another benefit of typing fast is a convenience. The effort to type is spread across all fingers, not just two or four fingers. You don't strain your hand muscles. The keyboard is built in a way that involves typing with all ten fingers.