When I'm posting on my blog, each articles can serve as a page to rank in the search engines right? So, I can create a good article about "Men's Fashion" and get the article to rank high with a good keyword % of "men's fashion" and then I can go on to create an articles o "men's clothing" and rank good for that as well right? What I'm really asking is.... When your keyword density is determined.....you only have to worry about that single article itself right? I don't have to start worrying because the keyword density of "men's fasion" decreased after I wrote about an article on "jelly and toast" correct?
Keyword density is no longer an important factor in SEO other than on the negative side with keyword stuffing. In regards to your question though, it is possible for two separate web pages to rank for totally different keywords and in fact all of your web pages should be written with this in mind.