Unrelated question: how do your hands look after handling coins so constantly as you do? Is there a slight sheen to them? Do you have less hair on your hands than you normally would, or more?
Same with enhanced sensitivity. I can fairly accurately tell you how many cards I pick up from a group. It's just practice, once you can do 2, you do 3, all the way up to 10, to 15 to 20.