They update individual areas based on available satellite imagery. You can look at the bottom of whatever map you are viewing and it will say when the image was taken. It will also try to trick you with copyright data showing it as this year, but both dates should be there. These folks are using google earth pro though. That allows you to view areas over time. To see when the images were updated. This is also how to discover all the Gitmo construction memes of a few years ago were not due to Trumps action as all the new buildings he was alleged to have built were in existence for quite some time prior to him taking office. The pictures were real, but presented without date context to fit the narrative Trump built everything you see on google earth.