How many keywords per post

i start to think that the most natural way of kw density is dont think about the kw density
imagine if u're not tricking and playing seo and is a normal blog writer
u dunno or never heard of bhw
how would u write it?
u wont repeat a kw easily more than 3 times right?

i think hitting title and h1 is more than enough

You can use 2 to 3 Keywords for 700 words of article. Kept your effective keyword in the title.If your keyword density exceeds 4% it may cause over optimization. So that fit your keyword in article as natural way.