The most important question to answer is "Why?" Why are we learning what we are learning. If we know the "why" our learning is meaningful and worthwhile.
The nature of knowledge has dramatically changed over the last thirty or so years. It used to be that knowledge was held in libraries. They were our cathedrals of enlightenment.
No more. Knowledge is accessible anywhere, at any time. This access is radical transformation of the nature of knowledge.
As knowledge is readily accessible, the need to retain knowledge "just in case" it might be needed at some future date is greatly diminished. Today, learning is done "just-in-time" that is, when the knowledge is needed to solve a problem, it can be found and used.
Knowing the purpose of learning, then, becomes critical. That purpose gives the learning meaning and relevancy that allows it to be used to solve problems that are important to the learner. Any learner, at any time.