Bestselling author Kathy Sierra has an interesting post on the motivations behind learning. She contrasts the just-in-time approach to the just-in-case one. Her point is that just-in-time is generally more effective. Unfortunately, most of us have learned via the just-in-case model. Most books are also structured around the just-in-case model, if you ask me.
The best advice in her post has to do with overcoming the limitations of just-in-case learning. It’s something she does very effectively in the Head First series.