Whether building a PBN, optimising a money site or trying to rank for any type of keyword, the status quo is that more content = better....but why? Well here's why: http://www.andreykurenkov.com/writing/organizing-my-emails-with-a-neural-net/ That's a pretty in-depth article on neural nets and machine learning that are employed to classify content, these may not be the exact techniques being used by the Google algorithm (they likely are, if not very similar) but nevertheless the underlying principles remain the same so here's the tl;dr: tl;dr More content is indeed better in terms of on page SEO because it's more likely to contain more words that assist search engine algorithms in classifying your on-page content. While this has long been held as a truism of SEO, it's particularly nice to understand why, after all understanding something can help you to game it. The OP found that near 1000 words achieved the desired result in terms of being able to accurately calculate the relevancy of a piece of text. Presumably Google will have more refined algorithms with better scores for less text but nonetheless, that's a nice ballpark figure to go on. Now one only has to extrapolate from the techniques used in the article by the OP that including more phrases related to the keyword that you're trying to rank for means good things...let's say from Google's keywords and related phrases tool contained in Adwords, where Google already provides the terms it's going to be using in it's relevancy algorithm. Again, perhaps you're already doing this but it's nice to know just how important this can be. It's not too much of a leap to assume that Google is assigning some sort of relevancy score for on-page content as part of their algorithm, i.e a page that scores 70/100 will presumably rank better than a page with a 60/100 relevancy score for a particular keyword (all other things being equal), so longer content with more related phrases worked in may just be the thing that gets you to that top spot.