What a great, thoughtful article. We run many workshops on content marketing and the number one idea we try to impress is: create a content plan!
Our workshop formula for (adult) learning is: Learn, Think, Try. We break all of our workshops into this formula so that we can teach ideas which include a little theory (learn) but mostly get people thinking about their business and trying to create something they can implement in their business today.
So, it’s interesting to see you categorize the content marketing process similarly.

The one thing I might change is the emphasis on case studies and testimonials. Yes, they are a necessary component in order to establish credibility. But too often case studies are thinly veiled sales copy, without real depth or value. Whether it’s case studies or other content, I think it’s important to focus on problem-solving content. If the case studies really do focus on that, preferably in a broader way addressing how the customer’s problem was solved beyond just use of your product, then that’s great. But, in general, as the competition heats up on the content marketing front, content is going to have to be really valuable and not overly-salesy to warrant reading.