It's a completely context-dependent assessment. I was part of a team a few years back where I was certainly not a 10x dev. It was a team of... around 8-9 folk

It's a completely context-dependent assessment. I was part of a team a few years back where I was certainly not a 10x dev. It was a team of... around 8-9 folks. 5-6 devs, PM, testers. There were jr/sr divides, but it was relatively smooth. My 20+ years of experience were helpful, but I wasn't 10x more productive than some of the lesser experienced folks on the team, and given the constraints and role I was in, there really wasn't a way to achieve that. I've been on other projects where the experience level and other factors really exacerbate differences, and I've absolutely been "10x" in comparison to the others on the project. The larger problems may come in with how you're treated, how you're viewed by management, etc. "In a controlled environment, the variation between most software engineers is much more modest." Well yes, but we don't usually work in controlled environments. With similar backgrounds/experiences, and strict project management controls in place, there's going to be far less variance possible.