Maximum Knock Retard - HP Tuners

I was watching the video on configuring the base tune file and in the section talking about maximum knock retard, it says that the stock values are excessive especially when tuning properly and we should decrease these values but I guess I don't understand this totally in part because I don't understand how the knock retard functions.

If knock is detected will it default to the maximum knock retard values or will it increase based on the severity of the knock until knock is no longer detected? If it increases based on the severity then wouldn't it be safer to maintain higher maximum retard numbers since it generally wouldn't reach the max values anyways?