There is also a difference between "understanding" and "understanding and being practiced" at something. In the real world is not necessarily important to be a

There is also a difference between "understanding" and "understanding and being practiced" at something. In the real world is not necessarily important to be able to rattle off information off the top of your head. More import is simply knowing that a thing exists, so you can go and look it up. Lectures are good at providing the latter.