Comment by tsumnia

Mastery by George Leonard touches on some of this; learners can fall into 3 categories during the learning process: Dabblers, Obsessives, and Hackers. Each one has strengths and weaknesses, but the core philosophy is that "mastery takes time". After 2-3 years of practice, you know all the moves in a school of martial arts, or all the chord progressions for an instrument. But its the "after" where you either continue to refine or move on to the next skill.

Anything advertising that you can learn X in Y days isn't addressing that "after" period. Once you've learned the skill, you need motivation toward applying it, which in turn refines your skills. Conversely, becoming hyper fixated can be detrimental to overall skill. "Jack of all trades, master of none" HOWEVER the rest of the quote goes "but often times better than a master of one"

Sometimes you gotta slog through the boring bits to progress.