The road is straight, climbing, with clean pavement. The vanishing point is a good ways off. We can keep plenty of speed at this point.
These are nice sweepers. The road is still climbing somewhat, so stopping distances are a bit shorter than they might be on level ground. If we were gaurenteed a clear road beyond the vanishing point, we could carry lots of speed, but we aren't so we don't. We note that the vanishing point is beyond the apex of the turn, so we anticipate that only moderate slowing will be needed in the turn, even if we should discover a hazard just beyond the obstruction.
This is a steeply descending turn, and the apex of the turn is beyond the vanishing point. We want to give up some speed early going into this situation. Someone from Kansas failed to do so a couple of years back, and collected upwards of a million dollars from the state of California, but I think he'd rather be on his motorcycle than confined to a wheelchair.
This is more like our first example. The road is straight and ascending, and it doesn't look like we have much to worry about in the way of cross-traffic. Check your 6 for the highway patrol and go!
Don't be fooled because you can see the road beyond the vanishing point. That rocky hillside suggests to me a high probability of loose gravel on the road, and there could be almost anything behind that tree. You know you're going to have to slow down for that oily-looking hairpin, so why not do it now and reduce your risk?
Here's another tricky one. You can see that the road is straight, and there's no traffic, and the pavement's good, right? Well, a low spot is a likely place for a washout. In another second or two, we'll be able to see over the ridge into this dip. Hold off on the accelleration until you're sure, and you'll likely finish the ride where you originally intended. Ignore the vanishing point, and you'll have nowhere to go when you meet a situation like this: Too Bad .