There are many roads that get used for "testing" by car mags,TV etc..
When results get published or transmitted it encourages people to go on them.
Another route is the Cat and Fiddle one that now has average speed cameras on it due to its use for fast driving.
There are similar roads near me...A4069 Black Mountain Rd for one...used by many "testers" such as Chris Harris. Police watch the road these days with hand held speed devices. Very popular with bikes, they use the Halfway cafe in Llandovery for stops too. Nice place to meet up and chat.
On open moorland roads you really need to watch for animals as well as the road.
They are not closed roads for races etc but many assume they can race. Not a good idea!
I am happy to "get a move on" but only if the road/conditions allow.
It is nice to drive these test roads as they do allow you to enjoy the car without excessive speed.