The last time I looked Google displayed as many characters as it can fit into a block element that’s about 600px wide and doesn’t exceed 1 line of text (on desktop). So – THERE IS NO BEST PRACTICE AMOUNT OF CHARACTERS any SEO could lay down as exact best practice to GUARANTEE a title will display, in full in Google, at least, as the search snippet title, on every device. Ultimately – only the characters and words you use will determine if your entire page title will be seen in a Google search snippet.
QUOTE: “The score is determined from quantities indicating user actions of seeking out and preferring particular sites and the resources found in particular sites. *****A site quality score for a particular site**** can be determined by computing a ratio of a numerator that represents user interest in the site as reflected in user queries directed to the site and a denominator that represents user interest in the resources found in the site as responses to queries of all kinds The site quality score for a site can be used as a signal to rank resources, or to rank search results that identify resources, that are found in one site relative to resources found in another site.” Navneet Panda, Google Patent
QUOTE: “Google will now begin encrypting searches that people do by default, if they are logged into Google.com already through a secure connection. The change to SSL search also means that sites people visit after clicking on results at Google will no longer receive “referrer” data that reveals what those people searched for, except in the case of ads.
Basically, SEO keyword research should be an ongoing and ever-evolving part of your job as a marketer. Old keywords need to be reevaluated periodically, and high-volume, competitive keywords (or “head” keywords, as opposed to long-tailed keywords) can often be usefully replaced or augmented with longer, more specific phrases designed not to bring in just any visitor but exactly the right visitors. (Who visits your site – particularly if they’re people who are actively looking for your services – is at least as important as how many people visit.)