How do they do polishing on Rolex case?

[hbk75]

Inside the servicing centers. Assuming that there are some scratches only on one side of the polished area of the oyster case (side without crown).

When they do polishing to remove scratches on one side of the case. Do they make sure that the other side of the case without scratches is even as well? Because when they remove scratches, they are removing some material as well. So if the other side does not have scratches, they do not need to remove any material. So the case will be uneven eventually?