WOW. I consider myself a total newbie to SEO, but I’ve been working on my Squarespace site for my small business for about 3 years and have read dozens of articles on how to improve SEO. So far, this has been the MOST USEFUL and information-packed resource I’ve found so far. I’m honestly shocked that this is free to access. I haven’t even completely consumed this content yet (I’ve bookmarked it to come back to!) but I’ve already made some significant changes to my SEO strategy, including adding a couple of infographics to blog posts, changing my internal and external linking habits, editing meta descriptions, and a bunch more. Thanks for all the time and passion you’ve out into this.
Lastly, it's important to remember that paralysis by over-thinking is a real issue some struggle with. There's no pill for it (yet). Predicting perfection is a fool's errand. Get as close as you can within a reasonable timeframe, and prepare for future iteration. If you're traveling through your plan and determine a soft spot at any time, simply pivot. It's many hours of upfront work to get your strategy built, but it's not too hard to tweak as you go.