We have about 40 ESD work stations around the building. I would guess that less than half of them are used on a regular basis. There is ESD mat cleaner available to personnel. The mats are tested by QC staff every quarter and straps are tested by the users daily. I assume that the mat cleanser is only being used if/when their mat fails the quarterly test. I am concerned that the integrity of the mat may be declining but not being caught until the quarterly test. I am considering implementing regular mat cleaning. How often do you think it should be done on the busy work stations and how often should it be done on the less often used work stations?