Never manually. But I use multiple browsers (Opera, Chrome, sometimes Firefox) simultaneously (well, in parallel) and I have separate work and personal computer

Never manually. But I use multiple browsers (Opera, Chrome, sometimes Firefox) simultaneously (well, in parallel) and I have separate work and personal computers. Sometimes I even use private browsing; and not only for "buying presents". But I believe this doesn't prevent me from Google knowing all about it. Whether I use one browser or other, private browsing or not. Some do-not-track extension which would completely block downloading and executing of tracking scripts might have help. But I'm not that paranoid. Yet.