Sure, we did keyword research, we recommended partnerships and widgets and architecture advice, but we didn’t step back and take a good look at our target audiences, what sites were meeting their specific needs in search results, and what we specifically could build into the product that would be far more desirable than what everyone else had (not even thought of yet ideally) to make sure our entire site is superior, resulting in the inevitable stealing of search traffic from our competitors.
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.