A few stories to illustrate:
1. I had a few friends that made it a point to learn a new technology every day of the month and blog about it. In the end, the friends had learned quite a bit, and even though they only had cursory knowledge of the subject, the structure allowed them to succeed at their goal to have a more general knowledge in their discipline.
2. I have another friend that started writing an application with the point for it to be the central product of a great new startup. This friend is not only intelligent, but very capable in the whole stack, self-organized, and I would have expected him to succeed. However, he lost interest in the end before go-live. there were competitors, and I think he lost the vision that he had in the beginning. He could still finish the product, but now he has another job. I credit this to lack of structure, which is not his fault; I've gotten no where near as far as he did on a myriad of ideas for products.