The great ongoing content density test. Below are test links by the purveyor of SEO myth.

150 words @ one target keyword

150 words @ two target keywords

150 words @ four target keywords with tabs

400 words @ one target keyword

400 words @ two target keywords

400 words @ four target keywords

250 words @ zero target keywords

250 words @ four target keywords

250 words @ two target keywords

250 words @ target keywords only in FAQ Schema

150 words with dark background @ four target keywords

150 words with fade-in text @ four target keywords

150 words with fade-in text below the fold @ four target keywords