## 4 Discussion
### Lessons Learned from the Design and Evaluation of Each Application Case Study
The CHISel application use case exemplifies how to manage the evaluation of a complex UI, while the application is still under development and highly confusing for end-users to understand in its unfinished and potentially unstable state. Trained HCI evaluators were chosen to conduct a thorough CW of specific tasks, focused on accuracy, user-friendliness, effectiveness, and efficiency. Their professional expertise equipped them to methodically explore each task, step by step, revealing subtle design flaws that might otherwise remain hidden. By combining domain familiarity with usability best practices, these experts pinpointed interface complexities, learned about system feature interactions, and assessed multi-user collaboration nuances. Additionally, the experimenter collected observational and verbal data from four CW experts as they went through the CW tasks. Along with the evaluators' own findings, this provided rich, specific feedback on the interface's learnability. As a result, the evaluation not only identified precisely where the UXUI needed improvement but also offered detailed, actionable recommendations for refining the software's design, ensuring a low learning curve and aligning it more closely with the domain-specific goals of the application. A thorough CW with trained HCI experts produces pinpointed insights for two main reasons. First, these specialists bring extensive knowledge of usability principles and design best practices, allowing them to dissect each interaction step with a clear sense of where problems typically arise and how to address them. They do not simply note that \"something's wrong\"--they use their expertise to diagnose the underlying cause of the issue, such as unclear feedback or inconsistency in interactive elements, and provide educated suggestions for improvements. Second, the CW process requires evaluators to follow a user's path through the interface task by task, rather than only testing random features. This structured, goal-by-goal approach uncovers specific friction points that might otherwise remain hidden. Because each task is scrutinized against explicit user goals, the resulting recommendations tend to be detailed and actionable, offering clear directions for the designers on how to streamline steps, redesign problematic widgets, or improve feedback mechanisms. Ultimately, this level of methodical analysis ensures that usability improvements directly target the real challenges users face, instead of applying broad, unfocused changes. The PLUGGY platform application use case review showcased the importance of a development framework employing a complex, triangulated approach, by integrating formative and summative evaluations with diverse methods such as persona descriptions, interviews, pilot field studies, paper prototype testing, usability testing, and expert reviews, collecting both quantitative and qualitative data. This multifaceted strategy is crucial for large-scale, multi-party development teams, as it ensures comprehensive coverage of user needs and system performance. Formative evaluations--including interviews, pilot studies, and prototype testing--are conducted early and iteratively to refine concepts and address usability issues promptly. These methods provide continuous feedback, enabling teams to make informed adjustments that align with user expectations and domain-specific requirements. Summative evaluations--such as expert reviews, the SUS and EMOTIVE questionnaires, and NPS--are performed later to validate the overall effectiveness and user satisfaction of the final product. Each method was selected to complement the data collected by the other methods: Persona descriptions help in understanding and empathizing with different user segments, ensuring that design decisions are user-centered. Interviews and pilot studies gather qualitative insights, while usability testing and paper prototypes offer practical assessments of interface functionality and user interactions.