Hello gercam,
Your going to get lots of different SEO's on here give you different views, but this is my answer....
I always recommend about 5 - 7 keywords per page as a maximum (when targeting competitive keywords.
However by doing this, you will also achieve many longtail keywords too.
eg: if targeting:- loan | mortgage | insurance | car
you may also gain positions for:-
car loan, car insurance, mortgage insurance. (hope you see the obvious, how this may work).
This is an example, and to be honest it wont be easy to do it with the keywords that i have chosen..... but..... Not impossible.
Hope this helps.