[vph]

This is not a tip. The author simply reported his natural learning curve. Naturally, you learn a lot at the beginning and later on you don't learn as much. The author went through this process and thought that because he didn't learn much "other things" at the end, he was doing the right thing, and he had made mistakes early on by not focusing only "the thing" he was supposed to learn.

No, he did not make mistakes by digressing into learning things that are related but might not be directly addressing his problems at hand.

Learning is complicated, as things that you learn help you in ways that you might not be even aware of.