It has been my observation throughout life that when people see other people are waiting for them to complete any task around 50 percent of those people go about their normal routine without any change. Another 25 percent speed up and make an effort to get out of the way as soon as possible to accommodate the next in line. That final 25 percent slow down and move like they are swimming through molasses.
I try and be in the fast 25, though I admit sometimes I slip into the 50 group. Actively push me, make rude comments or gestures and you might be able to motivate me to slide down into slow 25 mode.