I just thought I would post an example on how important consistency is in system development. Here is an example of a bad system :

Month 1 : 177 Bets with a Profit 20%
Month 2 : 133 Bets with a Profit 25%
Month 3 : 125 Bets with a Profit 22%

From here a lot of people would start betting the system

Month 4 : 115 bets Loss of 5%
Month 5 : 126 bets Loss of 4%
Month 6 : 110 bets Profit of 15%
Month 7 : 150 bets Loss 50%
Month 8 : 117 bets Loss 30%
Month 9 : 105 bets loss 40%

Alternatively I also have a system that does the following :

Month 1 : 5 bets with a Profit 400%
Month 2 : 7 bets with a Profit 300%
Month 3 : 9 bets with a Profit 122%
Month 4 : 3 bets with a Profit 105%
Month 5 : 5 bets Loss of 4%
Month 6 : 5 bets with a Profit 240%
Month 7 : 6 bets with a Profit 350%
Month 8 : 4 bets with a Profit 100%
Month 9 : 5 bets with a Profit 520%

I prefer to use this system altought it doesn't have many bets becasue it is more consistent on the results. ie 8 months in profit out of 9 whereas the other is only profitable 4 out of 9 months.

I would say you need a minimum of 2 years testing before you can declare a system consisitent.

Good Luck.