Setpoint for warning

We have an induction stove, which has a glass surface that usually only gets hot by conduction from the pan you use on it. The control panel displays H when a burner is hot but not on. My experience is that the surface never gets hot enough to be a problem wiping up spills because the wipeup cloth provides enough insulation so I ignore the warning. Presumably there is a temperature sensor in the element and a threshold for displaying the H.

I was cooking potatoes tonight and spilled some of the oil as I was flipping them. The stove duly showed H on the burners that had oil on them. I got paper towels and wiped up the oil. It didn't burn, but it was rather hot.

It got me thinking about the choice of a warning threshold. I can see the manufacturer wanting to make it low enough that nobody could get burned at the lowest temperature it comes on. That makes it low enough that people discover it is not a serious warning and ignore it. It seems like a standard problem that should have some standard thoughts about how you choose the threshold. What are they?