It's a public road, not a race track. You don't get prizes for saving .01 seconds in a curve. The primary goal is survival. Speed has to be adjusted to level that allows you to avoid hazards, be they vehicles, gravel, fallen tree branches, wildlife or potholes. If blind curves or blind hills mean you can only see thirty feet ahead, you drop your speed so that you can stop within that distance. The laws of physics will prevail regardless of the posted speed limit. Riding in the outer third of your lane will let you see further around a curve and let you be seen sooner by oncoming traffic. Apexes are irrelevant, position the bike to maximize your sight distance. Otherwise, you are just playing Russian roulette on two wheels.