It might be that different approaches to reading are more useful at different points in your life. When you're young, inexperienced, ignorant, inevitably mentally provincial, you might well gain most by reading widely and quickly in order to acquire perspective and a passing familiarity with a lot of things. Once you've built a reasonably rounded, if shallow, model of the world, and started to learn which parts of it you are most passionate about, you'll probably gain most by going deeply into those.

Breadth first search, then depth on the best matches, in other words.