The problem with sectionals to my way of thinking is that they measure the time of the leading horse at the 600 (or whatever) to the time the winner crosses the finish. For this information to be useful you would need to know the lengths a particular runner was from the leading horse at the 600.

A horse that was 12 lengths back at the 600 and finished close up would have run a faster sectional than a horse leading or close up at the 600, but in both cases you're using the same sectional time in your calculations.