Brex faced significant challenges with their Kubernetes namespace-based preview environments, which led to operational inefficiencies and high costs. These isolated environments, intended for testing, became increasingly difficult to maintain. Developers were pushing the limits of the Kubernetes control plane, resulting in unmaintained services and a reliance on staging for testing. This created a feedback loop that hindered developer velocity, as issues in staging affected multiple teams. Connor Braa, a Software Engineering Manager at Brex, highlighted the low cost of errors in the preview environments, which contributed to a culture of neglect. To overcome these hurdles, Brex adopted Signadot, which creates isolated sandboxes within a shared cluster. This approach drastically reduced the time for previewing changes by 80% and improved user satisfaction scores by 28 points. The infrastructure costs associated with developer previews plummeted by 99%. With Signadot, Brex could maintain a reliable staging environment while allowing developers to experiment without disrupting others. This shift also improved data quality, as developers could work with more realistic test data rather than temporary placeholders. The transition to Signadot led to a cultural shift at Brex, emphasizing both unit and integration testing before deployment. By keeping staging up-to-date, Brex avoided the pitfalls of relying solely on unmaintained environments. The change not only enhanced developer productivity but also addressed underlying business concerns related to costs and talent retention. As hiring developers comes with a hefty price tag, ensuring a smooth and satisfying development process became critical for Brex's long-term success.