YOU can test yourself in fast trading by roll down to "All index 15 min 145 periods at 14:05" and take positions long or short. Write it down and go up to next page and check the result. Before leaving this page you decide what you want to do now. Buy, sell or keep your position ,write down etc. Continue until "SP500 5 min 16:00". Remember only 3 percent of traders make money in the long run. The computers sometimes manage to sell at the very top point in each trend and buy the double amount of long positions at the lowest point in the trend. Human brain cannot think that fast in trading.