Is SEO a precise science or lucky guesswork?
I know fellow college (webmaster) whose website have enormous G. traffic (about 50k/d) without any effort from his side, regardless to SEO and basic rules about SE visibility.
His basic job is to steal content from the other sites, inserting a tons of keywords without any order and sense, website itself is full of tech. errors (CMS is pretty old) and no backlinks at all!.
So, he break every rule about SE visibility but still without any penalty from G., moreover the traffic constantly stay high.