I kinda of disagree with you Barny on that statement.

I would have more confidence in certain systems with 5000 bets over 6 months than that of a system with 100 bets over 12 years.

Over 6 months I would be more mindful with the seasons of racing.

You could easily back-test a system to work on Melbourne cup over 100 years of information. I still would not have confidence in that holding up in the 2012 Melbourne Cup.