The pinch test, thatch, and mat

There was a question in a seminar about how much thatch is too much. I first answered it by saying ideally we'd have no thatch, and would have only mat, and that we do want to have some amount of mat that varies depending on what type of surface we are producing. I used Beard's definitions of thatch and mat:

thatch: an intermingled organic layer of dead and living shoots, stems, and roots of grasses that develops between the turf…