If we don't see the market gain a second wind after our having made an initial entry, the conditional probabilities of getting the move in the other direction continue to increase. We are getting further confirmation that buyers can push the market no higher or sellers can push prices no lower. It is when we see that our initial position is not getting torched and subsequent market behavior is in line with our thesis that we can add a second unit of risk to the trade. We extract more from our trading by being largest when we're "rightest" and smallest when we're wrong.