Actually the police instructor on my "day with the police" told me to always do this to avoid the "idiots" coming onto the motorway

As for learners on the motorway, cant be a lot worse than a lot of the others already on there, maybe it will reduce the number of people who undertake the car in front as he's trying to get back to an inner lane rather than hog the middle lane having overtaken someone slower in the middle lane by moving to the outer lane whilst watching them undertake the middle lane.