You must calculate the value of the contract. Here is what happens-- The trader uses high margin compared to their TLNW. They have a few wins and begin trading more contracts as they win. Then , catastrophe strikes and they are wiped out. However, the trader who manages risk effectively by looking at the full picture stays in the game during the down event, loses a smaller percentage and starts winning again. In addition, the trader utilizing analysis of full contract value in calculations, is less inclined to get anxious and make desperate or stupid moves. The only edge a trader has is risk management. Every entry /exit method is known to all traders---it is just the ability to manage those entries and exits prudently that is an edge to a trader.