Clay is not ordinary dirt
Clay behaves badly in a way that surprises people used to general dust. Wet, it is adhesive and spreads under foot into a thin film that covers a large area from a small amount. Dry, it becomes a fine powder that becomes airborne easily and settles across every horizontal surface. It also stains porous surfaces and grout in a way that ordinary soil does not.
The method has to change with the condition. When it arrives wet, mechanical removal before any water is applied, because adding water spreads the film. When it has dried, vacuum rather than sweep, because sweeping puts the powder into the air. Applying one method year-round produces a poor result during at least half of the conditions. Recording which condition applies at a given attendance is worth noting, since the crew needs to arrive equipped for wet or dry rather than for both.
