If AT&T wanted its system to improve, it needed to be that change - it wasn’t going to happen by just sitting back and waiting. And similarly, that change was probably going to look different than the changes that had come before. Continuous improvement shifts how people think and act.
Predating the “continuous improvement” regime is not unique to Bell Labs. Bell Labs didn’t have a unique model. However, it does stand in contrast to any institution that we could create today. It’s important to call out this shift in context because it means that any organization starting today needs to take it into account. It is worthwhile to try to replicate outliers, but you need to consider what is different in doing so.