chosulman wrote:"So should we all be driving[...]so that if a vehicle comes the wrong way we can act or react accordingly?"
In general, I am in favor of planning also to a scenario where another road user will be going the other way, whether it's in a roundabout, a controlled junction, a winding road or whatever.
If the road is wide enough, it makes little difference because you can drive at about the same pace (in terms of being able to safely stop well within the area seen to be clear) and rely on your ability to brake and veer around the oncomer. If the extra space is absent, one should drive at a speed that allows to safely stop within half of the area seen to be clear, or less.