In recent years I've done more content marketing with clients than my own blog, which is changing.
We plan our quarterly where possible, focus on a dedicated weekend to either record and transcribe content, or in my case jam out articles, edit, and get the evergreen content going ahead of schedule.
Evergreen meaning not dependent on changing markets (easy to say, right?); we then write articles as you outline to match content we've found and want to add commentary and ideas to, but all of it is also adapted to keywords which give us ideas of what to write.
I do also love SEO tools like Serpstat.com that give us content articles written by others that rank on search and social; good to get an idea of what's been said, or needs restating. While not writing content to match only the keywords, they give a great idea of what customers are thinking (obviously with social included as well for impact). I listen more to my audience and peers, than sit down with folks, but living in a small town that makes a bit more sense.
That said, I do contact my network to get their ideas, especially people not directly involved in the subject, in addition to subject matter experts.