I think it is wise to get rid of junk as early as possible, if market is moving opposite to our trade there was something wrong in our analysis and so we should admit that and correct it by closing as soon as possible. First of all, you have to be very careful in not to enter any such trade that is more likely to go against you, but as its forex, any thing can happen, then you should do is use stop loss on all of your trades that you are entering.