Jerome Powell warns about not varying the annual stress tests on banks

As financial institutions and the financial system evolve, stress testing will need to keep up. When the next episode of financial instability presents itself, it may do so in a messy and unexpected way. Banks will need to be ready not just for expected risks, but for unexpected ones. Thus, the tests will need to vary from year to year, and to explore even quite unlikely scenarios. 

If the stress tests do not evolve, they risk becoming a compliance exercise, breeding complacency from both supervisors and banks. We might also, inadvertently, encourage the development of a banking system where, over time, all banks would look much alike rather than the banking system we want and need, one with diverse institutions with different business models. We simply can't let these things happen. 

~ Federal Reserve chairman Jerome Powell, prepared remarks for stress-testing conference at the Federal Reserve Bank of Boston, July 9, 2019

(As quoted in "Fed’s Powell Says Stress Tests Must Evolve to Avoid Bank Complacency: Annual exam must explore unexpected scenarios or it might fail to prepare financial system for next downturn," The Wall Street Journal, July 9, 2019.)