QUOTE: “The preferred domain is the one that you would liked used to index your site’s pages (sometimes this is referred to as the canonical domain). Links may point to your site using both the www and non-www versions of the URL (for instance, http://www.example.com and http://example.com). The preferred domain is the version that you want used for your site in the search results.” Google, 2018

Hi Noya, all the info suggests that dwell time IS taken into account in search ranking, and we know that Google measures time on page and bounce rate in Analytics, too. Plus the search engine gets smarter all the time. With the machine learning component of RankBrain, we wouldn’t be surprised if Google can tell the difference between sites where visitors stick around, bounces where the visitor gets an answer immediately, and bounces where the visitor keeps searching.

In 1998, two graduate students at Stanford University, Larry Page and Sergey Brin, developed "Backrub", a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[22] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random web surfer.
QUOTE: “The duration performance scores can be used in scoring resources and websites for search operations. The search operations may include scoring resources for search results, prioritizing the indexing of websites, suggesting resources or websites, protecting particular resources or websites from demotions, precluding particular resources or websites from promotions, or other appropriate search operations.” A Panda Patent on Website and Category Visit Durations

One concern we hear frequently is whether it is beneficial or harmful to repeat keywords. In other words, should we vary keywords (dog food, puppy food, and Purina) or repeat keywords (dog food reviews, dog food comparison, and dog food rankings.) The short answer is that the repetition is just fine, as long as the meaning of the phrase as a whole is sufficiently varied. In other words, dog food and dog food online are basically synonymous, and the content that one might expect to find associated with both keywords is the same. However, dog food reviews and dog food comparison indicate somewhat different content and therefore are appropriate to be used in tandem as keywords.
Optimizing the page for keywords is quite simple if we follow the basics mentioned in this article. As said above, use keywords in URL, meta description, Title and headings. I think it doesn’t matter how many times we use keyword in a page, but where we use keywords matters. In the blog content we can use LSI keywords which are probably the best keyword ranking approach in 2018.
This is why developing a list of keywords is one of the first and most important steps in any search engine optimization initiative. Keywords and SEO are directly connected when it comes to running a winning search marketing campaign. Because keywords are foundational for all your other SEO efforts, it's well worth the time and investment to ensure your SEO keywords are highly relevant to your audience and effectively organized for action.