The speed I drive depends on the specific situation.
I don't speed at all in school zones where the light is flashing for students coming to school or going home, because I knew a little boy who was severely injured when he was hit by a car and I would probably want to die if I did that to a child. I watch out for kids in parking lots too, because they could dart out in front of my car like my daughter used to do. If I see a kid playing anywhere near the road in a residential area, I drive well below the speed limit.
I do speed on the highway, depending on how fast the other traffic is going and the condition of the road, weather, etc. I don't care if the other cars are driving too fast for bad conditions, like heavy rain or snow, I will not do it too. I usually try to keep it to no more than nine miles per hour over the speed limit, even in good conditions. Of course here in Colorado, the speed limit on interstates is 75 miles per hour, so that is already pretty fast.