I'm curious - I want to know does Google check for duplicate content everytime it crawls a web page or once in 6 months or so.
Do this checking similar to what Copyscape does? Wouldn't it be a big overhead, how does Google handle it?
They haven't said how often they do it so no one really knows. But their "Panda" algorithm has been processed three times which would indicate they accumulate information over a period of several weeks and then do a bulk update of their index based on their accumulated data.