Optimize for how users are actually using the page — as opposed to how you optimized the page ahead of time — and you’ll see significantly better traffic.
Cyrus Shepard in an good blog post: My Single Best SEO Tip for Improved Web Traffic.
I have always seen the first focus on creating content that users want (both in content and usability of the medium of delivery). Some techniques related to SEO can be useful in tweaking how you go about managing your online presence but it is secondary to creating great content focused on users.
His article is really focused on putting a large amount of effort into tweaking the content. I think this makes sense for some important pages (and some important flows within a web site or web application). I think it is way too much effort to expend on most pages (the payback won’t be worth the effort).