Maintain a coherent vision of the user interface architecture. Create the initial vision during a "sprint zero" period — before any implementation has started — and maintain it through annual (or semi-annual) design vision sprints. You can't just design individual features; they have to fit together into a coherent whole — a whole that must be designed as well. Bottom-up user interface design equals a confused total user experience (the Linux syndrome). - Reinout van Rees