All of my lenses have required microadjustment, most of them +/- 5 to 10, but I believe one of them was 12 or 13. After microadjustment my 70-200 f/2.8L IS finally became the lens it was always rumoured to be and I sold my 85/1.8, 100/2, 135/2 and 200/2.8 primes. My 24-105 f/4L IS has exhibited excellent sharpness from 24mm to 50mm, very good from 50mm to ~70mm and respectable up to 105mm since the microadjustment. It's definitely a more worthwhile exercise than I thought it would be.
But why should we have to go through this? If the lens's focus needs a bit of tweaking and it can be done electronically, why can't it be done at the factory? I don't have two bodies that will both do microadjustment, so I'm only assuming the adjustment is lens-specific. I'm curious if anyone has any data to support or refute such an assumption.