How valid is the Keyword Density Theory?

Is there really a Goldi-Locks Effect for KW Density?

[Storyman]

Here and there I've been reading about keywords. Too low of frequency for the targeted keywords and the site's serp is nowhere to be seen. Too high a frequency of targeted keywords and there is a chance the site will be banned. The Goldi-Locks Effect dictates that there is a targeted keyword frequency that is just right.

It has been suggested that the sweet zone for targeted keywords is somewhere between 5-10% keyword density. After downloading a demo of one of the keywords programs that analyzes the keyword for a website, I noticed that most of the sites have few keywords that fall in the suggested 5-10% range. In fact most of the keywords have a density in the 0.5-2% range.

I'm wondering how valid is the keyword density theory? Has anyone had expereince where they targeted keywords to achieve the Goldi-Locks Effect for keywords and seen a change in their ranking because of the change?

Or is the keyword density factor a lot of malarky?

[phantombookman]

KWD is definately an issue, I battle with it regularly.
The nature of my sites create the problem and force me to ignore Google's own cardiunal rule, build for the viewer not the search engine.

Some pages require the mention of Widget far too often
I have found these pages will get dumped
If you then change some to Wi**et it will then rank
Seen it time and time again

Interestingly, unlike duplicate content, a KWD penalty is much like hidden text etc, 30 days and you can come straight back in if you have made the changes.

There is also an age/change issue that comes into play.
I have older pages ranking really well with 15-20%kwd
If I were to lift another page to that level it would be out.

I do keep meaning to try testing to pin down the figure but normally I just play it by ear

[SiteTechnician]

"a KWD penalty is much like hidden text etc, 30 days and you can come straight back in if you have made the changes"

PhantomB, can you explain this mechanism of coming straight back in after 30 days? Are you implying that the penalized site is tagged for review 30 days later?

Thanks.

[Animated]

what i do is check the KWD's of the top 10 sites for my keywords and try to have mines around that % too, but KWD is just one of the many things that make asites rank higher.