For a while now we have been optimizing for 3 keyword phrases on every page. These phrases are different on every page. My question is, why shouldn't I optimize for 10 keywords? Or 20? Is each keyword separated by a comma given a weight, and the more phrases you have, the less weight each of them is given? I know meta kw isn't that big anymore, but as an isolated best practice, is fewer kw's better?
as far as i think, the answer is yes. It is called theme bleeding. this was said by charles heflin in his site. You could search on google and go to his site to understand it better.
I think that the best way you could handle it is by conducting a survey. For example if the keyword you are targeting is vehicles, you should analyze the competitors' web pages, and see what phrases they are aiming at. Use the Total Backlink Analyzer. It's a free tool you get from the i-net. For instance you could have like 30 keywords but none of them would be compatible with the page if they don't get lotta entries in SEs.
You could use 3 to 4 keywords per page. but then you should use other terms related to it within the article you write. For example. If you are writing a page on something related to milk. then cheese, yogurt, curd could also appear on the page and thus the search engine would understand what is it about. This is called latent semantic indexing.