... connections, and even edge-case behavior. It s about pressure-testing, not just checking boxes. Cross-device and cross-browser Especially for web apps. What looks perfect on Chrome might break on Safari or mobile. I use tools like BrowserStack or even just my own devices to double-check responsiveness and performance. Feedback loop I always run a closed beta with 3 5 trusted clients or peers. They give brutally honest feedback. They ll catch things I m blind ...