Lighting assessments have been part of low-vision rehabilitation for decades, but more structured and evidence-based approaches have emerged in recent years. In Denmark, a mixed-method semi-structured protocol for lighting assessment was developed and tested as a pilot study from 2017–2019, and it showed promising results, in that it improved the visually impaired participants’ quality of life. Innovations are often developed in pilot studies, but implementing new approaches across communities of practice poses difficulties due to both individual and organizational norms. N-Lited is an implementation project that entails the dissemination of knowledge and instructions as well as practical trials, and its protocol has been implemented in seven low-vision centers from 2022–2023. Based on participants’ observations, document analysis of the framework, and a midway evaluation that assessed the potential for scalability and diffusion, this paper discusses the learning and change processes in the interpretation and role of the lighting measurements and lighting assessments in this project. Beyond mere instrumental learning, the findings reveal that it is crucial to address how individuals learn how to explore and question the difficulties that reveal mismatches or reconfigurations of values, norms, and assumptions to ensure a successful implementation of the method. The changing role of lighting measurements, from instrumental to more reflective, also illustrates the importance of the practical application and learning-by-doing aspects that are essential for learning how to reflect and “think with the metrics.” Furthermore, metrics and tools are an important part of the community of practice’s shared language. The uncertainty of navigating between the uniformity of the protocol and the flexibility needed for incorporating the method into individual professionals’ practices and the various organizational contexts emphasizes the relevance of the process of learning how to manage methodological innovations in practice.