Create and propagate information that helps people to create and ship the software...
Everything else is details on this. I was the senior software tester for multiple projects. I got paid more than most everyone else, because I owned the above. I helped and did everything, and spent as little time as possible, NOT doing anything else.
However, most people spent tons and tons of time NOT doing the above. The created very little new and useful information, and propagated very little. The company would make up for this by hiring LOTS of people, to try and create more information. Lots of time, people were given my stuff, in an attempt to expand on it.
Personally, I spent a very small fraction of my time on regression testing. A little more on verification. But most of my time creating and propagating information.
I would spend time creating models and predictions, and watching carefully what would happen. I would look at errors, user expectations, standards, behaviors and functionality. And barf stuff out as quickly as possible. And some percentage of time was coming up with larger and better explanations.
I was never done, and I never could work enough to find them all, and I was never satisfied. There was always rich veins of information to be uncovered and passed on.
At some point it shipped anyways...
Sometimes I was there for the next version, sometimes I did other things.
My personal satisfaction, was knowing that I had a substantial impact on what shipped. And that it was better for me being there.