The big mistake made by traders is thinking and expecting trading to be a favorable game. Trends both short- and long-term do exist but not 100% of the time.
The correct way to control positions is to only hold them once they prove to be correct. Let the market tell you your position is proven correct, but never let the market tell you that your position is wrong. You, as a good trader, must always be in command of knowing and telling yourself when your position is bad.
Your exposure and risk is much higher if you let the market prove you wrong instead of your actions removing positions systematically unless or until the market proves your position correct. You decide what is correct according to your plan.
You never want to be in a position that is never proven correct. By making the market prove you correct in order to hold a position is acknowledging that trading is a losers’ game and not a winners’ game.
What makes this strategy more comfortable is that you must take action without exception if the market does not prove the position correct. Most traders do it the opposite by doing nothing unless they get stopped out, and then it isn’t their decision to get out at all — it is the market’s decision to get you out. Over time it has proven to be the rule which keeps the losses small and keeps a trader swift and fast to take that loss.