Hi Barney,
I used to correspond with a gent who used this system but going back 4 starts and didnt consider the increase in distance factor.He did quite well on gallops and dogs.

The decrease in Win % could be to do with age - the best racing years of a thoroughbred beng 3 - 4 or 5 .From there on in the majority of horses a gradual decline in performance is expected.

Cheers
darky