## 5 Conclusions  
In this study, drilling experts made comparable errors in using the VR and the real prototypes. There were no significant differences in evaluating the execution of the work processes. There were no significant differences between VR and reality in terms of the number of required interactions. Thus, these partial results of the VR user test are transferable to the real world. However, there were significant differences in the time required to complete the top drive connection process and rating the _efficiency_ dimension of the UEQ. Drilling experts required more time for this process in VR, but still rated the VR prototype as more efficient. We assume that the better subjective evaluation in VR can be attributed to the novelty effect. Furthermore, there were no significant differences in the subjective evaluations of the prototype; however, the VR prototype received higher ratings. In the interviews, the drilling experts who tested the prototype in reality were more critical, and mentioned more optimization suggestions than the experts who tested the VR prototype. The evaluation of the physical prototype provided more insights into the optimization of the prototype than the evaluation in VR. However, several usability problems could be identified in the VR environment. This study shows that, at the current stage of the development of VR systems, user evaluations in VR are suitable for identifying usability issues. An investigation of the user experience and acceptance should be conducted using real prototypes. If the VR experience of the participants increases in the future and interactions with virtual content are further improved, subjective parameters such as user experience can also be evaluated more accurately for VR environments. Despite these limitations, VR user evaluations can optimize the development process. Based on this study and the accompanying development process, we recommend the following approach for the user-centered development of control rooms for onshore drilling rigs:  
1. Development of an operating concept: 1. Creation of menu structures with click dummies. 2. Selection/development of suitable control elements and indicators. 3. Expert evaluation of the menu structures. 4. Development of a virtual prototype. 5. User evaluation of the prototype in VR with a focus on usability issues. 6. Optimization of the virtual prototype. 7. Re-evaluation of the virtual prototype in VR. 8. Optimization of the virtual prototype. 9. Manufacturing of the prototype. 10. User evaluation of a real prototype on a (drilling) simulator, focusing on user experience and usability issues. 11. Optimization of the real prototype. Expert evaluations should be conducted with system users and usability experts. Steps 1-3 should be iterative. We recommend one to two user tests in VR. Depending on the number and severity of the identified usability problems, Steps 4 and 5 should be repeated. This approach reduces the number of real prototypes to be produced, which in turn, reduces the development costs and time. Future studies should investigate the extent to which this approach could be applied to other product types. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13148319/s1](https://www.mdpi.com/article/10.3390/app13148319/s1)]([https://www.mdpi.com/article/10.3390/app13148319/s1](https://www.mdpi.com/article/10.3390/app13148319/s1)), Figure S1: Description of the tripping process for the participants; Figure S2: Description of the tripping process for the participants; Figure S3: Description of the top drive connection process for the participants; Figure S4: Mean ASQ scores for the statement \"Overall, I am satisfied with the amount of time it took to complete the tasks in this scenario.\"; Figure S5: Comparison of success rates for performing the introductory tasks; Figure S6: Comparison of the success rates in the simulation of the second tripping process. **Author Contributions:** N.H., S.K., and C.S.