I never bothered to time shots when hunting. I have been more impressed with dead birds, than how fast they were killed. That having been said, I agree, that constant practice, and a lot of shooting sure helps build speed.
I also feel that it is helpful to have someone knowledgable work with you from time to time, to critique your form . It is so easy to get into bad habits, and another set of eyes can spot that quickly before the habit gets ingrained.
I prefer my Browning A-5 shotguns to anything else for bird hunting. The Sweet 16, the Mag 20 or Mag12 all get field time. I think I really shoot the 16 best.
While I will never be in then class of the guys mentioned in that article, I have always held my own when it is time to count the birds in the bag.
Nemo Me Impune Lacesset
"The trouble with our liberal friends is not that they're ignorant; it's just that they know so much that isn't so.".........Ronald Reagan