It's important to understand that stipple removal will expose deficiencies in the ceiling. Once stipple has been removed, we have to skim the ceiling 3 or more times to make sure it is smooth. In addition, supplemental wrk may be required if the ceiling is not flat and is wavy instead. This can happen in order homes, lathe and plaster or water damaged drywall. This is also why you wouldn't use drywall with a thickness of less than 1/2"