I was just thinking the same thing; I was talking to a fellow trader last week and i said that after the first three races, you tend to know how the day will pan out.
Interesting point. I am currently putting together a database of all the data I've ever recorded and while I am keen to look at similar races across time, I am starting to wonder whether the best information/signals are from the first hour of the markets.
I also noticed that in a recent blog that Peter W said he accelerates his risk into the market based on how the day unfolds.