One of the biggest challenges in developing a system is to plan the trade and trade the plan. Even if a systems plan has the potential to be profitable, traders who ignore the rules are altering any expectancy the system would have had. There is no such thing as a plan that wins 100% of the time. After all, system losses are a part of the game. But losses can be psychologically traumatizing, so a trader who has two or three losing trades in a row might decide to skip the next trade. If this next trade would have been a winner, the trader has already destroyed any expectancy the system had. Automated trading systems allow traders to achieve consistency by trading the plan.