I could say that I don't believe people who have screwed up in their writing are blocked, because all they have to do is delete the screwed-up scene and start over, and bingo! Their block is gone. However, I prefer to say that all block is real and awful to the writer experiencing it, and there's nothing to be gained by dismissing their problems in this way. Let's be respectful and compassionate. It works better in the long run than one-upmanship.
There's been a lot of research into the effects of exercise on creativity, and the effects of being outside rather than inside on it too. Various studies have shown that exercise, preferably done outside, really does help in even the most severe cases of creative (not just writers') block. I've found it's not enough to just go out for a walk, though: I have to be mindful when I'm walking, otherwise I end up stewing over the problem that's probably blocked me in the first place. Pay attention, be present, still your mind. It works.
This is such a good illustration of the problems inherent in developing rituals in order to write. Whether you feel you have to use a favourite pen, work in a particular cafe, or indulge in self-destructive habits like getting "really stoned", drinking, or not sleeping for days, it's restricting. Because there will come a time when that pen is discontinued, that cafe is closed, or you end up getting so stoned that you can't write at all (and even if you don't, the quality of the writing you do when under the influence of anything mind-altering is often poor, so why do it?).
Better, I feel, to avoid getting too enmeshed in rituals and habits with your writing. Work wherever you can. Work in different ways, using different mediums, different approaches. Be flexible and adventurous and disciplined.