I suspect Microsoft rolls them out about as quick as they can. If they don't they know the hardware makers will blame MS. But at the same time, I hope Microsoft runs them through a small battery of tests to make sure they are compatible with the standards, and Windows. That said, there are 1000s of different manufacturers making many 1000s of components. It would take some considerable resources and MS surely doesn't make any profit from that testing - other than not getting blamed.
I have seen this too - but frequently those updates are beta, or for unique scenarios that only affect a few people. For everyone else, the existing drivers still work and [hopefully] they (and MS) are going by the philosophy of, "if it ain't broke, don't fix it!" I for one, never update a driver just because a new one is out there - with the sole exception (maybe) of graphics drivers.
My main problem with letting the individual hardware updaters check for updates is, if not careful, you can end up with several, or even many updaters all running in real-time with Windows, hogging resources.
