what is going on here? how does agile provide for continuous and long-term progress?
The popular slogan Red Green Refactor describes an experiential learning style made popular by test-driven development. The tests themselves provide a ratchet that prevents regression. But the skillful practitioner learns to select tests that also advances broader deeper understanding of the problem at hand.
While doing, one must reconcile expectations with observation. Thus forms operational intelligence of two types, that which assimilates confirmation, and, that which accommodates the unexpected. Not only is the act completed, ability and curiosity grows.
We say direct experience leads to deeper and broader knowledge. Deeper means we can build on this, broader means we have to look elsewhere.