Barry Boehm's cost-of-change curve—the idea that late changes in software are exponentially more expensive—was valid in the 1970s-80s but no longer reflects modern reality. Three forces have flattened the curve: modern IDEs and tooling, automated testing and CI, and modular architectures. Agile further reduced costs by shortening feedback cycles, and AI-assisted development is now accelerating that trend again by making code revision dramatically faster. The real bottleneck today is no longer coding effort but feedback delay. The practical implication: teams and managers should stop treating requirements as documents to be perfected upfront, and instead treat them as living artifacts that evolve alongside the product. The biggest risk in modern software development is waiting too long to learn, not changing too late.
