Six weeks before enterprise client demos, Deloitte's security team rejected our entire authentication system because it didn't meet their SSO requirements. We had to implement enterprise-grade single sign-on integration across multiple identity providers (Azure AD, Okta, Google Workspace) while maintaining the simple email/password option for smaller clients. Then KPMG requested custom assessment templates that our flexible builder couldn't handle, they needed industry-specific compliance questions we hadn't designed for. I had to extend the question builder architecture to support custom question types and regulatory compliance tags without breaking existing functionality for other clients.