I have always found it difficult to try to optimize for more than a few keywords/phrases per page. Most times I will target one per page if at all possible, using content marketing (blogging) to optimize for others, even writing multiple articles about a keyword to gain authority in it.
I am not saying it's impossible, many factors would determine that, like competition, etc... I just personally think it's easier (all the way around) to limit the number of keywords per page...
