My favorite teacher in grade school, and echoed by my favorite teachers later in life, told me that the most important thing they are trying to teach us is how to learn because we'd all be learning for the rest of our lives.

I still strongly agree with that sentiment, but the difference/problem with learning as an adult is two-fold: why I am learning, and how much time I have to learn/apply that knowledge.

There is a difference in learning material to 'ace' a midterm/final exam, versus learning something to figure out a novel way, or picking up a new technology, to accomplish some task (e.g., at work). Part of the difference is who decides what can be "pruned", and especially when. I think back on all the 'stuff' I knew I would never need again once the final was over. Admittedly, I wasn't always correct, but age and experience increased my hit rate, and what subjects I under or over estimated could be whole other threads.

I am retired now, but have gotten into learning, mostly just for fun, some of the most complex (nasty) subject matter that I never had time for before. If I want to go off on some tangent, or deep dive, I can. The amount of free (or inexpensive) courses out there is wonderful and exciting.