Microsoft's Black Tuesday bandwidth impact?

Every month I look at my upstream bandwidth graphs and I see no blip in the hours before 3 am on Microsoft's Black Tuesday. I would think that with the thousands of PCs out on our network downloading updates around that time that I would see *something*. I know every Black Tuesday I see my three PC's blinking a logon screen. Are MSFT's monthly updates really a non-event in regards to internet bandwidth? Frank