I'm looking at this graph from here:
The answer providing the above graph explains how kinetic friction is constant. However, the graph tells me that after static friction is overcome, there is a period of time where the kinetic friction is decreasing towards this constant value (the green part of the graph).
Given this, why is the force of kinetic friction still considered constant? It seems to be a function of velocity (approaching a certain asymptote as the velocity of an object approaches infinity).