They are testing and testing again, overlapping various tests for different types of user satsifaction, and so on.
Google's business absolutely DEPENDS on their ability to measure user satisfaction.
Perhaps Google needs to rethink their testing methods, since user satisfaction seems to be at an all time low. I am hoping that a review of their stock trend since March 25th prompts some rethinking of their definition of "user satisfaction". [marketwatch.com...] - (set chart to the 6 month range)