Soaking these mats is ridiculous. The material they are made of is waterproof, not absorbant. No amount of soaking is going to do a thing for a mat.
They all cut well until they get too many little grooves in them from the rotary cutters-- then they don't cut as well. When yours gets that way, flip it over and use the other side until it's worn out too, then buy a new mat. Don't waste your time soaking.