I'm not a big fan of "just sit down and write anything," either. It's easy to go off in the wrong direction that way, and then the idea of going on even when you know something is very wrong, instead of going back and fixing it, is even worse. And yet, no writing is wasted if you learn something from it. And I know that it is possible to fuss too long over a certain section and that there is a time to move on regardless. And I also know people who are very prolific and work very well by keeping up their momentum.
I have often suffered, as many of you know, from long bouts of writer's block, which are related to, if not intimately tied up with, depression. So I know that beating yourself up for not writing does not work, and can only make things worse. Sometimes it is best to do something else writing related (research or beta reading, for instance) so that you feel less useless and discouraged and not incidentally keep your hand in to a certain extent. Some people would say, "That's no way to get things done." (Or worse that writer's block is just an excuse and a way of getting people's sympathy when you are too lazy to write. Except that anyone who has ever experienced a long period where they were blocked can tell you, you don't get sympathy except from other people who have gone through the same thing, because other people just don't understand it. Some may be sarcastic and dismissive. Some may try to be kind and supportive but even they can't sympathize in the fullest sense of the word.) But as for not getting anything done, many people who have this problem can be very productive in the times between. I think that if I sat down every day and tortured myself for hours trying to write when the words just aren't there that I would eventually learn to hate writing and give it up entirely. Instead, I have written eleven books and a bunch of little stuff of various sorts, and writing remains my great love.
So what I would say (and apologies for the long digression) is that it is not only important to find out what works for you (and in the early stages it might take a lot of experimentation with different ways to find out what that is) and to do it that way in spite of other people trying to convince you that another way would be soooo much better, BUT to also be flexible enough to recognize for yourself when the time comes that something else might work for you, at least for a while. It is possible to switch your methods for each new book, or between drafts, or just in the middle of what you are doing.
There are a lot of "rules" of writing but the only one true rule is this: Do what works.
