Just as an example, thinking back to my history teacher, he was a wonderful teacher. Really created an interest in history. Yet at least half the curriculum and most of our brain power as students was used to memorize useless trivia. Take for example, having to memorize the names of the counties or the eight lords proprietors. What does that really matter vs understanding how government works, and why it was designed that way. "Why?" is an important part of history, yet so little time was spent on it vs names and dates.
Saw similar things across so many of my classes -- a focus on the "easy to test" memorization of trivial facts with little emphasis on causes and effects. Even most of our science classes were about memorization, not understanding.
Makes you wonder how much better it would be if we put emphasis on "why" and "how" rather than "what year was so and so born?"