Speaking to an African friend of mine about this and what I classed as a sad depiction of hunting surprised me with his answer.
He said it is very rare for an old Dagga boy to drop to the first shot and it is common practise, due to their strength and the fact that always use solid shot to gain penetration, that they pump bullets until it stops moving, on the run or otherwise and regardless of the sight picture.
I mentioned that some shots were on a going away animal and he said that makes no difference, once targeted they must stop the animal at all costs regardless of meat damage.
Looking at it from that point of view then I suppose it makes sense, no matter how distasteful it seems, rather than have a wounded animal running off to suffer over many days.
Incidentally, my friend grew up in Africa and his father was a PH.