I think storyboards are important in planning out the page, and for some people, even planning out a whole chapter, depending where you want to submit it. Publishers and magazine companies usually have a page limit requirement, and for that you probably are better off storyboarding to manage the pacing.
It's also handy for aesthetic reasons, composition and what not.
I personally would prefer a more spontaneous approach since I don't like restricting myself and rather draw 'in the moment', and wouldn't do as much as briefly sketching circles for current page before diving into the final draft. I don't think that's for everyone though, as you can easily mess up, especially for long stories (like I totally have u_u)