Just the other day I was in Assurity, giving my favorite talk about efficient testing (based on "Rapid Software Testing" course and my personal experience). One of the arguments I made (after Michael Bolton in his time) was "use new tests other than old ones". Then someone from the listeners asked: but how do you do regression without using old tests? It got me for a second, because that was an awesome question, a new way to look at it. I mean, no one ever asked that in my presence. When you get question like that, it means that audience listened carefully, processed and understood what you were saying. It also means you get a chance to look at something from a new point of view.
So, I thought for a second, and then I realized: yep, I'm totally doing regression testing without using old tests. And that's how I do it: I don't use scripted test cases at all. What I use is a list of test ideas that structures my testing and serves as a backbone, as a starting point for my testing. So each time I do regression testing, I do it differently, because I don't have steps to follow. Each time I have to think: how would I test this thing, knowing what I know about it right now? So it's always a new test, and it's never out of date.
Another awesome thing was that after my answer people who asked me this realized that they do practically the same thing! They do have scripted testcases, but they never stick to them, and often they don't even read them. So they are actually doing new testing each time. "So why do you need steps written down?", - was my next question. I hope it will do some good. ;-)
I absolutely love it when I can actually say something useful to another tester and understand it immediately that it was useful. Far too often I get this feeling that a person listens to be polite and then goes about their old business, and maybe even uses some of my insights - but I never get to know about it.