...is that some days, you don't have any ideas that would produce a piece beyond your average quality. Thus, by writing that day, your average quality of writing goes down, not up.
What's the alternative? It's to write more selectively, and publish only your best and most worthy work. It's the approach Paul Graham takes with his essays, for instance. You get around a dozen a year, and they're all amazing.
However, I think the greatest danger in writing is in not doing writing enough. Being able to do a decent piece when you're off or completely uninspired has value, and you'll bring your "skill at writing when uninspired" up (and such a skill certainly exists).
But how about your readership?
That's tricky. You always want to write good things for your readers, so that their lives or enriched. It's tough when the gears are grinding and the output isn't that great. If you find yourself in that scenario and you're uninspired, I'd give you one piece of advice -- keep it short.
A short, intelligent argument, quote, or interesting fact keeps the train of writing going along the rails. And I feel like it's hard to write a bad very short piece. You make a succinct thought with an interesting little bit to back it up. It'll at least be somewhat thought-provoking.
Yet, still, it can be torturous to write during those uninspired moments. But if you stop writing, it can be very hard to get going again with the consistency needed to really build your skill, put great thinking and arguments together, and connect with a readership. And all good writers have down times -- so you'd best learn how to write something OK during those periods if you want to write.
I've had a lot of success with writing every single day and then posting the best two per week. Since I started doing that, I've gotten tons of emails saying my writing is better than ever. But actually my writing is the same as ever-- I just post the good ones. So in the same way that posting every day lowers your average quality, writing every day but posting intermittently raises your average quality. You also build a stockpile of good posts so that when you're not inspired, you have some stuff in the can.
As a side note, some of my highest rated posts were written on days where I felt uninspired and didn't want to write.
I guess that thinking about above or not your average quality is counter-productive and you should rather think about sustainability. In former formula you're stressing yourself about squeezing everyday a good idea (focus on quality only), in later formula you focus on acting continuously in order to produce better content on the long term (focus on quantity first then quality). As it has been said many times, quantity strategy trumps quality strategy on the long term.
I think that you should write as often as possible. It is through this tedious process that the best pieces come out and are polished. As the adage goes practice makes perfect.
Question from a reader -
You have maintained your commitment to being prolific which is made even more exceptional by the fact you are travelling around the world at the same time.
I realise your article on being prolific is about this, but accepting that I'm going to release a lot of crap before I realise something good is a tough wall to knock down. My biggest issue writing anything seems to be that it feel insufficent. Naturally no post I write has the length of Steve Yegge, the persuasiveness of Paul Graham, the content of Unqualified Reservations etc. etc. and while I can consciously accept this, there seems to be some mental block. How do you go "that's sufficient" and release it into the wild?
There's two basic approaches to being successful as a writer. The first, we could call the "Paul Graham / Derek Sivers" approach. This is where you explore a lot of ideas privately, go forward with the best ideas you have, and edit and polish the hell out of everything before you release it into the world. If you do this, and you've got talent as a writer, and you've got important ideas - then you're going to consistently only release masterpieces.
The second way is to just write a hell of a lot and know that a number of the things you write will turn out quite well, but your average quality level will be much lower. We could call this the "write every day no matter what" approach.
Let's be honest: My blog is pretty cool. It's not nearly as popular at Boingboing, Tuckermax, or that weird housewife who writes about her kids, but I have a pretty steady readership who all post comments and get something out of the site. Since I started around a year ago, I've averaged 1200 unique readers a day (half of that is thanks to huge spikes from digg and such). My blog hasn't made me rich, but I've probably made a few thousand dollars, which is a nice side effect. More importantly it's made me a much better writer, and has helped me chronicle the past year of my life.
What I'm saying is this : I can't help you build the next Engadget or WWTDD, but I can help you get started to building a moderately popular blog.
First you need decent hosting and Wordpress. Don't mess with blogger - no one reads blogger blogs because they all look the same and don't have cool plugins that you need. I know you can customize it and all, but stop arguing and do it my way.