The policies that work best under ideal conditions may yield terrible outcomes when conditions differ. Policies that fare better across lots of conditions may be preferable, even if they aren’t the very best under idealised circumstances.
Professor David Levy taught the history of economic thought when I was a grad student at George Mason University. For much of that history, economics was political economy. A combination of the study of markets, policy, politics, and institutions. Professor Levy had a particular interest in what he called robust political economy: policies and political institutions that might not be best when the world works like a whiteboard model, but that do not fail too badly when the whiteboard is wrong.