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Forum Moderators: mademetop
IMO, the best way to answer the question is to write the pages as they most make sense to the user. It's a cliché, but for good reason. The SE's like natural language pages and are getting better and better at sussing them out over time, and that should continue. I would not go around stuffing kw's into the pages for the sake of getting the kw's into the pages, unless doing so conservatively doesn't look at all odd or strange, and is either a neutral or positive change to each page's intended communication to users.
FYI the SE's have filters that account for such things, and over abundance of a single kw phrase sitewide can actually work against a site in some cases, especially earlier in the site's history.
OTOH, I have more sites where the core kw probably is found on every page -- or close to it.
It really does depend upon lots of factors.