The author of Proverbs crescendos his litany of purpose for compiling the teachings contained therein with this goal in Proverbs 1:6, "To understand a proverb, and the interpretation; the words of the wise, and their dark sayings."
The implication seems to be that we keep learning more so that we may better understand what we have already learned.
Here again, the New International Version enhances our understanding, "… for understanding proverbs and parables, the sayings and riddles of the wise."
I quote that to emphasize the word, "riddles" for "dark sayings."
One thing the disciplines of counseling, coaching, and mentoring have in common is the task of helping people process what they have already internalized. Processing leads to understanding. Sometimes it is one additional ingredient, like salt in a stew that brings out the flavor of the whole.
Just because we think we have already learned something does not mean we are done with it forever. It may be that our understanding up to this point has been useful and adequate, but like any tool, there may be uses and applications we have not considered, complexities of meaning that we have not grasped, and implications we have not pursued to their intended ends.
By adding to our treasures of knowledge and wisdom, we can deepen our understanding of what we have already learned.
There is a great beauty to that reality.