I'm pretty sure it used to be compulsory to pull over on the left before turning right when on the open road, and was a regular question in license tests when I first got my license in the '70s.
I think it may have changed when they changed the give-way at intersections rules (in the early '80s?) - now reverted. That was supposed to make it easier to turn right and improve traffic flow, but seldom worked well - especially when people turning left didn't bother to indicate.
It would certainly differ from much of (for example) Europe were that the case, where the following traffic would be expected to wait or to pass safely on the inside if possible. Mind you in a road system where you can have traffic merging from the centre of the road, anything is possible I suppose...