Who Questions What Works: When Should We Retest Our Assumptions?

Successful models are built on assumptions that can become so ingrained over time they are mistaken for reality. This creates a significant risk where we continuously update our methods without ever questioning the fundamental problem-framing, which may have become obsolete. The case of Moody's before the 2008 financial crisis illustrates this danger, as the agency adapted its models but failed to challenge core beliefs about a rapidly changing mortgage market. The true challenge, therefore, is not just monitoring performance but periodically re-evaluating whether the foundational assumptions that led to past success are still valid.