[mst]

I take it you are talking about calibrating a lens on a reference body ........ without any disassembly?   
This basically amounts to "the standard zero offset"   (offset being amount added or subtracted to the norm).

I assume they can do both, with and without assembly.
 

 I wouldn't return a lens for calibration unless it could not be corrected within the AFFT facility.

Similar here, I have used the Service for very few lenses so far.

However, I also understand those who switch camera gear regularly or use several bodies do prefer to have all lenses calibrated to default vaules.