We have shared the driving for 17 years of fulltiming. We started out swapping drivers every 2 hours and have never changed. We both love to drive and while the driver can "glance" at something interesting but can't really see all the beautiful things along the way. We do almost the same thing when we go out for a day of exploring. Dutch drives to the farthest point and I take over and we meander and stop at all the viewpoints heading back home.
Another big plus for us is that the "driver" isn't tired when we stop for the day. We open up then relax, go out for the night or visit with neighbors.
As far as learning every emergency in advance, there is no way to do that but I wouldn't give up the opportunity to drive on what might happen but that is just us.
A dual interstate is a great place to learn and the traffic can go around you if necessary and you do have shoulders if needed.
Our 3rd day out I was driving our Dodge dually with our Carriage behind and I mentioned to Dutch that there was a tunnel 5 miles down the road & I thought I should pull over as I had never "done" a tunnel. He said there was plenty of time to pull over. I reminded him again at the 3 mile mark and he had the same reply. When I saw the sign for 1 mile I told him I was pulling over. He said, "don't do that. You have to drive through a tunnel sometime, why not today. I gripped the wheel and stayed pretty close to the center line but made it through. I will say that once on the other side, I pulled over when there was room, loosened my grip on the wheel and said "Your turn". I had move confidence and knew Dutch was confident so now I to through big cities, little towns, bridges and tunnels. Oh yeah, I always seem to be the lucky one with construction too!!!! We do time if that if we have to drive at night I can do the driving.
I hope your DW eventually drives as it really is enjoyable. Di