Final answer:
After the Development Phase, the User Testing Phase follows in which users test the system to identify areas for improvement, leading to the refinement of the design.
Step-by-step explanation:
The phase of in-house system design that follows the Development Phase is the User Testing Phase. After the development of a system, it is crucial to test its functionality and usability with actual users. This phase involves prototyping, testing, and refinement of the design. Users interact with the system to identify any weaknesses or areas for improvement. Based on user feedback and performance tests, the design may be refined to better meet user needs and address any issues that were not apparent before. This may require returning to previous steps in the design process for further concept generation and selection, an integral part of the spiral design process.