Here's an interesting article about memorization. The part about increasing your speed I think is the most pertinent to counting.

"With typing, it’s relatively easy to get past the O.K. plateau. Psychologists have discovered that the most efficient method is to force yourself to type 10 to 20 percent faster than your comfort pace and to allow yourself to make mistakes. Only by watching yourself mistype at that faster speed can you figure out the obstacles that are slowing you down and overcome them."

http://www.nytimes.com/interactive/2...rets.html?_r=0