It's 2019 so can you share what changed from 2017 to 2018 then 2019?
LOTS! The SEO industry is primarily about keeping up with the latest algorithm shifts that Google makes. As a result, techniques differ year over year. Last year was the year of infographics. IMHO, they don't bring as much benefit in 2019. Longer blog articles work better now I heard. Just my opinion. But I'm the nutcase who is constantly googling, "best seo techniques in October 2019" ... "best seo techniques in November 2019" etc.