That's why it's called a speed limit, emphasis on limit. I believe limits should be set at a point such as you describe - a speed which reasonable people would consider clearly unsafe for a road. Drivers should then use their judgement of the corners/visibility, the current conditions, and their vehicle to choose a speed safe for their particular circumstances - this will obviously vary widely for different parts of the road, different conditions, and different vehicles. Setting speed limits to a point where you can safely drive the slowest sections of the road in poor conditions makes them effectively recommended speeds rather than limits, and I believe this trend has (and will continue to have) a negative effect on driver skill levels.
That's why it's called a speed limit, emphasis on limit. I believe limits should be set at a point such as you describe - a speed which reasonable people would consider clearly unsafe for a road. Drivers should then use their judgement of the corners/visibility, the current conditions, and their vehicle to choose a speed safe for their particular circumstances - this will obviously vary widely for different parts of the road, different conditions, and different vehicles. Setting speed limits to a point where you can safely drive the slowest sections of the road in poor conditions makes them effectively recommended speeds rather than limits, and I believe this trend has (and will continue to have) a negative effect on driver skill levels.