During the last hangout for webmasters, Google employee John Muller answered a question about using the URL Settings tool.
So, one of the webmasters asked whether Google takes into account these settings, or they are needed only for site owners.
In response, Muller assured that the settings made using this tool are indeed taken into account, but webmasters often make mistakes.
He said that search engineers sometimes even ask the Google Webmasters team to contact site owners to correct errors ...