Personally, I don't believe in shifting so much. Not for commuting. My commute is almost completely flat and there's many days I NEVER shift. Not once. I stand and pedal to start moving and get to a good cruising/spinning speed. I typically only shift then when I need to haul ass and need a smaller gear in back.
Plus the ability to run bar-ends in friction mode is so awesome. I never have to worry about adjusting derailleurs. And I can shift through the whole gear range in one shot if I want to. Of course I never do that, but I will shift through 2 or 3 gears at once sometimes. Makes for uber quick downshifts when coming to a stop.
I'm also not obsessed with cadence. I spin at whatever cadence is comfortable.