Blogging dilemma from Seth Godin: write for regular or occasional readers?

Marketing guru Seth Godin made an interesting point earlier this week:

Every time I write a post, I have a dilemma.

Am I writing for you, the one who has read more than 2,000 of my previous posts over the last five years? The one who has bought (and read!) so many of my books and is all caught up on my history?

It matters, of course, because I can take shortcuts, it changes the perception of my tone of voice and I can skip a lot of the preliminaries.

Or am I writing for you, the first-timer, the person who found this post on Digg or Delicious? If it's you, then I should take my time, write a bit more, put some background links in, etc.

There's no easy answer.