They're actually very accurate. But they don't count posts made in certain areas like the journal area. Their definition of last week means starting on Sunday, I believe.
They work fine for comparing boardies on a relative scale.
Which, of course, will never work for certain boardies who work on absolute scales of black and white, right and wrong, good and evil, black hat/white hat, has a cape/doesn't, in or out, up or down, etc. Comprehension of real world spectrums and reality is prohibitive to collecting children's books.