Use your keyword list to determine how many different pillar pages you should create. Ultimately, the number of topics for which you create pillar pages should coincide with how many different products, offerings, and locations your business has. This will make it much easier for your prospects and customers to find you in search engines no matter what keywords they use.
As I had a teacher at school who was always really picky on how to draw conclusions I must say that the conclusions you drew for your health situation might be true, but dangerous. For example: If slightly more women than men suffer from health deseases it could be wise to write the information toward women. But, if you take search behaviour into account thing could look a lot different: It might turn up that men search more than women or that (senior) men are more present on the net than women.
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. 
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