Well, you may have ended up a bit better ranked on those specific words, but I am sure it was not helping in the end, because, topic covering other topics would just be less considered, and this would end up into less pages being well ranked on other search queries, the one you even did not think about at first, and most likely the one to bring the most visits as well.
If you really want to optimize on keywords, write articles about them, good ones, specifically targeted for each one of your targeted ones, and human friendly of course. They should be good articles in which you just do not forget to repeat the good keywords more than once, but only when it's useful, for real.
And Use them in the article's page title.
This is far better than trying to pretend all of your web site's pages are related to these keywords, even when it's not the case at all.
I mean, here, we talk about SEO, and SEO is one of the most used words, do you see any spam indexing here ?
nope, we just use the words we need to write what we want to talk about. My point is the good keywords should naturally be used in a web site, no need to try to add weight on the randomly.
You'll get better results if you work on content.