A post-a-day blogging challenge is probably one of the best ways to develop your blogging habit. That doesn't mean a daily blog post is necessarily a good thing, or that you'll want to keep up that pace for the rest of your life. But to instill the habit, a daily effort is key. Just do it.
It's true that a certain frenetic energy develops during a blogging challenge. There's nothing relaxing about it, and once the newness wears off, the grind begins. Why, it's just like work! That's really the point, too. To blog successfully, you need to do it when you least want to, and you'll be rewarded somewhere down the road for your efforts. Hopefully, that reward will come when you are launching your own blog book tour.
That said, read this article about slow blogging to put things in perspective. Then think about how you can create quality and enjoyment in your daily blogging experience, without too much attachment to Google ranking or search engine optimization. After all, there's nothing better than loving your work, and in this case, it's just another writing venue, authors. Love of blogging is a good thing, so find a balance that works for you and be committed to creating the blog that will serve you on many levels.