Not an easy task to master and I must admit when calling races I did not always get the "also rans" in the correct order though, mainly in dog racing, I did try.
Always a good thing too to again be able to call an incident such as a galloper/faller as it happens but again not always possible especially if it happens out the back and the glasses are on the front. I can mainly speak with dog events but luckily at some tracks I didn't need glasses so that gives you an overall panorama of the track and field.
I would suggest that if you watched hundreds of races a week the points outlined in the opening post would be more common than not.
We are spoiled now with a vision of the race compared to having to rely on the picture being painted through the radio speaker as in previous decades - perhaps race calling style has altered over the years as now the audience can sometimes see as much as the racecaller could ever tell them, if not more.