That's the interesting thing, once you 'know the road' you know all the places where you can't see the road surface but because you know where the road is in the terrain ahead you can make optimised judgements about visibility to oncoming traffic, comfortable cornering speed etc. Also you'll know which corners have passing places which allow two vehicles to pass comfortably at speed. A lot of people not used to single track roads are frightened by local drivers coming round corners 'too fast'. Often it's because people don't realise that to keep on the left you need to take an extreme outside line which means steering away from the corner into a passing place and back again as you go around. I tell people this when they come to visit and they usually find it a lot less stressful driving here afterwards.