Examples I see of this every day, when driving to and from work. A car will choose to stay at approx 50km/h. And it's a reasonably good N road with a hard shoulder but overtaking chances are few due to the occasional blind bend or oncoming traffic during busy periods. A long line of commuting traffic inevitably builds up but these drivers will happily hold up them up for 20km+ and never let any traffic pass them.
I think it leads to risky behaviour as people in a rush further back tend to overtake the long line of cars trying to get passed the slow moving car at the front.