Short "case study" at LinkedIn [0] http://engineering.linkedin.com/developer-happiness/getting-code-production-less-friction-and-high-quality about how they cut release latencies by 80-90% by reversing the "ice cream cone of death" [1] http://engineering.linkedin.com/sites/default/files/InitialState-Fun.png:
There's one particular snippet that strongly resonates with what I've experienced at multiple jobs (emphasis mine):
*Team ownership of quality*
Quality is the responsibility of the *whole team*. Quality control is most
efficiently achieved if software quality is considered at *every step in the development cycle*. A software quality process will benefit from an appropriate distribution of test automation ownership between teams cooperating in a software development effort.
In other words: QA aren't the only ones responsible for tests. I would go a step (or several) further and explicitly suggest that testing needs to be considered at—or an integral part of—the design & planning processes. Rich Hickey goes even further in his talk about "Hammock Driven Development" https://www.youtube.com/watch?v=f84n5oFoZBc (highly recommended: TL;DR; people start work before fully understanding the problem space).
Things seem to be trending up at WMF, especially w/ the Web engineers' big strides in end-to-end testing. However, as the article suggests, you need to attack the quality problem from both ends—perhaps even emphasizing unit tests (shortest feedback, cheapest, least fragile).
0: http://engineering.linkedin.com/developer-happiness/getting-code-production-... 1: http://engineering.linkedin.com/sites/default/files/InitialState-Fun.png, thanks to Zeljko for introducing me to that fun term, much better than "upside-down pyramid"