Personalized disambiguation can be really handy. I'm a hobby woodworker, I've recently bought a vintage Record #4 hand plane and wanted to learn more about it. I found out this model was manufactured in 1939-1945.

So without thinking I type record plane 1939-1945 into Google. And guess what? I get information about hand planes, pictures of hand planes in the images section, links to ebay auctions for vintage planes etc, and in between these there were only a few results related to aircraft combat during WWII.

The same query in incognito mode doesn't return even a single link related to hand tools.

I'm implying that Google "learns" over time that I'm more interested in ruby the programming language and that a jeweler would over time get more gemstone related resources.