Unstructured learning wins
There are two types of learning: structured and unstructured. The first is like reading a textbook from the start to the end. The second abandons all formal progression through learning material. There's one reason why those who follow an unstructured approach end up ahead.
When you go through a formal course, you're expected to progress from one level to the next. Chapter one, then chapter two.
In the end, you complete all the course material, but that time must have been spent on the course material. The time spent reading chapter two is time not spent doing something else.
What's different about unstructured learning is that you can jump from one level to the next, and to different places on the same level, a lot more freely.
When you set out to learn something, there's usually an outcome in mind. I want to learn X to do Y. Going chapter by chapter is one way to get to doing Y, but there are many paths to being able to do Y.
When you have an unstructured approach to learning, you learn things about that particular learning process that guide you to a more effective way of learning. With this "learning feedback" you can figure out that certain material may be better for learning a concept than others. You can jump to the parts of textbooks that teach it the best. You can use any material that teaches you.
As you progress through the learning in an unstructured way, you have the option to ensure that whatever is teaching you is the most effective at doing so, which can't happen if you restrict yourself to following whatever a course gives you.