This is kind of a constant step, just like you wont have to do steps one and two again, you'll probably have to do this one plenty to make up for it! Its important to keep things fresh and up-to-date so updating your sites is definitely benefitial and worthwhile!! Blogs on the other hand need nearly constant attention, if people have nothing further to read about they'll go looking for it somewhere else...

So, basically, always keep updating your sites, they're like your little mini businesses treat them as such and give them the attention they need in order to grow and work better for you!