Before i reply this, first we need to know what is keyword density? It the 5 of the text or similar text present in a fix sequence on a page like IF we write “Learn Good Food making” 4 times and “how to make good food” 2 times the Good food is there for 6 times and density of this “Good Food” Keyword may be higher then the other.

Now many SEO books say that a 3 to 5 % relevancy is good for a page. Wow in that case a page can be ranked anyway by typing a keyword 5 times….NO WAY.

IF you have a niche website than you just need a natural flow for a keyword or set of keyword on a page with little OFF PAGE work link back links etc. And you are done. But if you have a competitive field website then it not %age that works more but a set of rules are there.

What i experience that if we are targeting large number of keyword for a page its not important that every keyword must have 3 to 5% density in fact in most of the cases for large page with more keyword that a keyword is good if it has even 1% of density. Now even if you have it more than 3% that will not guarantee that you will be ranked. Mind it!!! Google do not like keyword stuffing and may ban your website or put that on penalty.

Sites that has very less competition and niche, has an edge with keyword densities.

At this phase, I think a little bit of keyword density is okay, I do not suggest to follow 5% or 7% density guidelines. It should rather be natural, and as per competition to website.