Can someone me explain the landing logic?

So I saw the code and it says that for the drone to recognize that has landed, it needs to be in a -1m/s – +1m/s , not have acceleration for one second, and less than 12.5% hover throttle)

I don’t understand the 12.5% hover throttle condition. Like what’s stopping from using a throttle outside this range that also allows for the copter to descend or is it impossible to descend outside this range?