"By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third, by experience, which is the bitterest." - ConfuciusAccording to a very recent HBS paper titled Learning by Thinking: How Reflection Aids Performance, Di Stefano, Gino, Pisano and Staats argue that by "reflecting on and articulating the key lessons learned from experience, a person boosts her self-efficacy, which in turn has a positive effect on learning. In this respect, (...) the process of transforming a tacit into codified knowledge requires a cognitive investment that generates a deeper understanding of this knowledge."
In other words, reflection is as important as experience and is often underrated. If you haven't read the post on sense-making, you should, as both subjects (learning and sense-making) are correlated.
Learn smarter, not harder.