I'm not quite sure if frequency of posting guarantees success. OK, I guess it depends on what Jeff calls success. If success means improving your own writing skills, ability to express yourself, organizing the thought process, enhancing research skills, and other aspects of personal improvement, then indeed, frequent posting can (but not necessarily will) help achieve success. But I suspect that the majority of bloggers (especially beginners), equate success with the number of hits (readers). Now, this sort of success does not depend on the frequency of posts. In fact, many accomplished bloggers (Steve Yegge, Michael "Rands" Lopp, Robert X. Cringely, Joel Spolsky, to name a few) are not frequent posters. As a subscriber to many blogs, I prefer authors to focus on quality of their posts rather than quantity. Somehow Jeff managed to achieve both, but most bloggers simply cannot produce more than one quality post per week (at best). I'm not saying that you should not keep writing more often, but if you keep posting crap, I doubt that you will gain a wide audience.
I think that the primary indicator of success in blogging (or anything else for that matter) is the desire to write (or do whatever you desire to do). If you have this desire, i.e. if you cannot keep yourself from writing (and it does not matter whether you have readers or not), then do it, and do it as often as you can. If you are lucky, maybe someone will mention your blog in a popular publication, you will be successful in gaining readers. If you do not have this desire, i.e. if you can keep yourself from writing, write for personal improvement, but do not expect to gain many readers, and please do not post too often.