The answer is what ever looks real and like it was written or explained without trying to seed keywords.
In 1000 words you want to say black cock about as much as you would if you were having a real conversation, or reading a descriptive essay, about black cocks.
There is no 'perfect' or 'set' number for keyword density, that is 'hired gun' smoke and mirrors.
Write your text legitimately and keep on niche, and you wont ever have to worry about silly percentages like that.
|