When a task is completed at the Computer Repair Shop, the changes are immediately incorporated into the full product. This avoids the extra work related to the integration of all items before delivery. Tests greatly facilitate this integration : when all tests are passed, the integration is complete. Deliveries must be the most frequent possible. Continuous integration and testing significantly reduce the cost of delivery.
The team is not overworked. If this happens, the schedule must be reviewed. A tired developer works badly. Based on the scenarios defined by the customer, the team creates test procedures for verifying the progress of development. When all functional tests pass, the iteration is complete.