In agile our highest priority is to satisfy the customer through early and continuous delivery of valuable products and services. We achieve this through rapid build, measure, learn cycles.
Research shows that 80% of features are rarely if ever used. Managers don’t know what customers want so they put in everything they think customers might want. This means that business requirements are untested hypotheses about customer needs.
In agile we believe that simplicity is essential. If you can focus on what customers really want you can cut project time and cost by 80%. To achieve this you need to test your requirements and design concepts early and often.
This is why you should be deploying to production every sprint. If you cant deploy a feature then watch how customers are using your product, show them a design concept or prototype and find out what they think.