Yes, they did not come any more revolting than Beagle. But to the point and a reinforcement of the question, why?. As Zeibart points out there is literally a world of difference between a home base, home base sortie and a world wide route trip. Even if the quality of training really is better now than in the past and I do not sense that it is, then jumping seats at an early stage of training can only add strain to the students need to feel "comfortable" in the aircraft and thus more ready to do that for which he is there , to assist the captain in the safe and efficient operation of the aircraft. If that aim was better achieved by training co's in both seats then so be it but nobody has convinced me yet.