Ask HN: Can search engines improve results by checking the time spent on a page?

Recently there were some discussions regarding the fact that Google is no longer producing high quality results.

I’m not sure wether this has been already implemented by any search engine but I thought it for a while: can search results be improved by also checking/ranking the time spent by the user on the relative page? Maybe by playing a bit with URLs and redirects?

For instance, if a lot of people are visiting a page and are not leaving it (not going back to the search results), then most probably it means that the page is pretty valid (high rank). If a lot of people are visiting a page and are leaving it after few seconds, then most probably it means that the page is not valid (low rank).