Efficient software engineering requires balancing speed and intentionality by building to the minimum product specifications while maintaining high-quality coding standards. Over-engineering, which attempts to predict future needs, often leads to increased complexity, slower development, and more bugs, making it inefficient compared to quality-engineering, which focuses on modularity and extensibility. The story of building a to-do list app illustrates common pitfalls like rushed development cycles and skipping clean coding practices, which can result in a tangled codebase that is difficult to modify. By using strategies such as narrow interfaces and avoiding unnecessary dependencies, engineers can create flexible architectures that allow for easy modifications and future enhancements without starting from scratch. Drawing from experiences with projects like FitNesse and Graphite, the text emphasizes the importance of separating core application logic from changeable dependencies, thereby saving time and avoiding potential headaches associated with over-engineering. Prioritizing clean code, unit tests, and low coupling, while deferring complex decisions until necessary, enables faster development and more reliable outcomes.