This ^^^ is what I kept hearing/reading while I was preparing for my test. .......And, yes, they said you should drive at the prevailing speed limit. IIRC part of the reasoning is that if you are driving as fast as you're allowed you aren't tempting other drivers into making errors due to them being frustrated at your slowness. The flip-side of this is that you should get past slower traffic as soon as it is safe to do so so that you don't fall into the frustration trap."making progress"