Comment on WordPress Site Title Tag SEO 2016 by SEO Dave.
Take a read of SEO Tutorial – Domain Name Optimization for a more detailed discussion on whether to brand or fully SEO a site via the title tag.
I don’t have the budget Amazon has, so there’s no way my sites are going to be world famous for the name of the site. For example it’s not going to be generally known there’s an awesome WordPress SEO theme under the brand “Stallion” at Stallion SEO Theme, so there wouldn’t be much point adding something like “Stallion” to the end of every pages title. On the other hand for Amazon they are a global brand, adding “Amazon” to the end of their SERPs makes a lot of sense, they’ve spent millions on brand awareness.
SEO wise it’s usually better to set “Best SEO Title Element ON”. This assumes you’ve optimized all the title elements of your pages, if you have a site you made before understanding the value of adding relevant keywords to the title there might be value setting this to OFF if it adds relevant keywords to most pages (would have to be a highly niched site).
Regarding the value of the title element/title tag I’ve not seen any evidence to suggest Google has recently downgraded the value of what you add to the title, it’s still the most important on page SEO element.