Having a different description meta tag for each page helps both users and Google, especially in searches where users may bring up multiple pages on your domain (for example, searches using the site: operator). If your site has thousands or even millions of pages, hand-crafting description meta tags probably isn't feasible. In this case, you could automatically generate description meta tags based on each page's content.
The emphasis on tools, meaning plural, is important because there's no one magical way to plop your website atop every single search results page, at least not organically, though there are best practices to do so. If you want to buy a paid search ad spot, then Google AdWords will happily take your money. This will certainly put your website at the top of Google's search results but always with an indicator that yours is a paid position. To win the more valuable and customer-trusted organic search spots (meaning those spots that start below all of those marked with an "Ad" icon), you must have a balanced and comprehensive SEO strategy in place.
SEM is better for testing than SEO. Because you can immediately turn SEM paid ads off and on, it’s a great strategy for testing. You can quickly revise your ad copy, target new audiences, and change landing page content to test your new tactics. This flexibility allows you to see differences in your strategies immediately. You cannot accomplish this through SEO, as it would take too much time to make changes and monitor differences in results.
QUOTE: “The average duration metric for the particular group of resources can be a statistical measure computed from a data set of measurements of a length of time that elapses between a time that a given user clicks on a search result included in a search results web page that identifies a resource in the particular group of resources and a time that the given user navigates back to the search results web page. …Thus, the user experience can be improved because search results higher in the presentation order will better match the user’s informational needs.” High Quality Search Results based on Repeat Clicks and Visit Duration
QUOTE: “I don’t think we even see what people are doing on your website if they’re filling out forms or not if they’re converting to actually buying something so if we can’t really see that then that’s not something that we’d be able to take into account anyway. So from my point of view that’s not something I’d really treat as a ranking factor. Of course if people are going to your website and they’re filling out forms or signing up for your service or for a newsletter then generally that’s a sign that you’re doing the right things.”. John Mueller, Google 2015