#16 is interesting because no one really knows about it. Myself and a former colleagu did a test on it about 4 years ago and published our results which conculded what you are saying. Since then I’ve been careful to follow this rule. The only issue is that often times using the exact kw does not “work” for navigation anchor texts. But with a little CSS trickery one can get the code for the nav bar to be lower in the code, prioritizing contextual links. I’ve also seen sites add links to 3-5 specific and important internal pages with keyword rich anchor texts, at the very top of the page in order to get those important internal links to be indexed first.
Website owners recognized the value of a high ranking and visibility in search engine results, creating an opportunity for both white hat and black hat SEO practitioners. According to industry analyst Danny Sullivan, the phrase "search engine optimization" probably came into use in 1997. Sullivan credits Bruce Clay as one of the first people to popularize the term. On May 2, 2007, Jason Gambert attempted to trademark the term SEO by convincing the Trademark Office in Arizona that SEO is a "process" involving manipulation of keywords and not a "marketing service."