I ran some KW-percentage analyzer on a few pages once.
For the life of me, I can't remember if KW counts were high or low, really beside the point.
I found myself getting this bass-ackwards. The point is to write naturally.
I presume the major engines are constantly trying to improve their machine algorithms.
Part of this must be KW counts (although many other things must factor in.)
This implies that any 'optimal' KW count is a moving target at best!
In the Nevada casino game of Keno (Chinese lottery), there are two strategies:
1) Chase the 'old man' which means to bet on recent numbers.
2) Let the 'old man' chase you, or stay with your favorite numbers.
As SERPs ranking is very NON-random, I recommend strategy #2.
Let G and Y (and sometimes MSN) chase you.
How to do this?
a) Write your own stuff. Don't scrape. Neither 'stuff ' nor scrimp on important words or phrases.
If your writing isn't the greatest, hire somebody.
b) Write as clearly and naturally as possible. KW counts will take care of themselves.
c) As the engines refine their algorithms, and the better they do so,
Their ideal KW percentages will slowly approach yours!
Don't chase the search engines with imaginary KW percentages. Let them find you. -Larry