Charlie mentioned The Cult of Done Manifesto recently, and his post does a good job of framing that philosophy as it applies to his work and life. As I've thought about how it might apply to me, I've come to the conclusion that there are places where it would work well, and places where it probably shouldn't be used.
I think that the approach would work well in areas where there is more than one right way of accomplishing a task. Writing comes to mind immediately - things like blogging & writing stories. NaNoWriMo was an extreme exercise in "getting it done." For me, an approach like this would lessen or eliminate those posts which seem to be in perpetual edit mode.
But I can't imagine a medical doctor pretending to know what he or she is doing, because "pretending to know what you're doing is almost the same as knowing what you are doing. Nor would I anticipate very many successful medical practitioners adopting the approach that "failure counts...so do mistakes." Similarly, for the work I do - appraising a property, arriving at an opinion of value, and then reporting that value in a proper manner - this approach probably wouldn't work well.
That said, there are times when I've used elements of that approach within my job. The notion of setting aside the idea that there will be a finished product and just getting things down, for example, has come in handy several times when I've hit a certain point where I am stuck.
Like so many things in life, it seems there are two extremes. The two extremes to avoid here are working so hard to achieve perfection that you never accomplish your goal, and cutting so many corners to get finished that your final product is worthless. Each of us will tend to one extreme or the other, depending on our personality and what we're doing. Avoiding these two things will allow us to be both more productive and more pleased with the outcome of our labors.