I'm going to be honest, rather than just make up a number, and tell you I don't know how many times I've told other writers to "Just keep writing." I know it sounds like the advice from that delightful fish movie, but I guess that's OK. Couching life lessons in comedy is like coating vegetables in chocolate.
For me, I don't believe I ever find a problem with the doctrine of writing whenever possible. Always having some means of note-making close at hand is great because there are times when you're not actively seeking inspiration that it does strike. Personally, I like to have a couple of my favorite pens, some kind of notebook and something electronic (these days, my smartphone is the latest incarnation of portable electronic notepad). It may sound redundant or overprepared to some, but I like to be ready for the ideas that just come to me and I like to be able to chase down the others.
Writing doesn't just happen by itself. There comes a point when you need to put pen to paper and start writing something. Really, just write. If you've got an idea, great. If you don't, write anyway. I say that because whether you have something fresh and stimulating to fill your blank page or you're just stringing together words, you need to keep moving forward (not that you're unwriting). It's all progress. Even if what you're doing just ends up being the warm-up for something else entirely, that activity still had its part to play in getting you to the good stuff.
I never try to retain who first said it, or wrote it, but it still holds true that you shouldn't be concerned with the quality of a draft, whether first or second or fifth. You can rewrite anything you've written, but there's nothing much to be done with a blank page but to put a bunch of words on it.
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