Earlier this week Darren Rowse @ProBlogger.net answered a user’s query "How many posts should I post?" as a blog post here. And he expressed his views about the frequency of blog posts by highlighting the pros and cons of daily blogging.
While I agree with him that there’s no perfect answer, I also feel that it really depends upon your niche, brand and various other criteria. So there could be an answer perfect for one and not for another. You need to find that out by yourself.