It's interesting how many of my areas of knowledge are based on one intensive period of study, often many years ago. Even if it's something I put into practice daily, once the habits and mental models have been created, there's often no imperative to revisit the learning material, or keep up to date with changes in the field. Good for breadth, but concerning in some ways.
Follow
While in the past it would have been fairly standard to learn something once and have that skill for life, with the rate of progress today (with technology, distribution of information, etc), the point at which a skill or knowledge becomes obsolete is rapidly accelerating.
