Chaos Days provide particular benefits if run weeks or months before major changes are deployed to production, or ahead of traffic peaks such as Black Friday for e-commerce sites. Ensure there is a sufficient gap between consecutive events to allow for learning to be distilled and improvements to be applied. For one client with a very large platform (1,000 microservices, processing 1 billion requests on a peak day), we found that 2–3 Chaos Days each year was a suitable frequency for their context.