According to a recent blog post by Sean Donahoe, you should be posting to both your social media accounts and through your email lists.
Here is his infographic to explain it.
About Sherry Fields
By Sherry Fields: By a very circuitous route I find myself in Internet Marketing. I have been on this journey for about 12 years, but really only dabbling in it until recently. With over 25 niche sites my creative juices get a great work out. As a published author, I have learned 'stick-to-it-ness" and getting the job done which means all the bits that are not creative too - you know the 'slog" stuff. You'll find me on Facebook, Twitter, JV Focus, Warrior Forum, LinkedIn and Google+