No, that is not true. I used to work on road signage systems, where we would use test vehicles, sensors, and math to figure out what the correct signage should be for various sections of road. The standards are primarily concerned with maintain a margin of error for the "worst" cars on the road, i.e. the ones that meet only the minimum inspection requirements. What happens once that margin of error is exceeded was anyone's guess, but practically could be wildly different for specific scenarios that had more to do with the off-road environment than the exact parameters of the road. Two roads with identical bends would receive the same signage regardless of whether under steering through the curve would land you on a sidewalk or in a field or over a cliff.