Thinking that trading another pair is an edge to your first trade in wrong, you will experience that when your first trade goes well, your edge one will eat it’s profits and viceversa and this is not counting that sometimes both could turn bad which will just add confusion to your trading…
Let the winners run and cut losses short is known as good advice but without a system backing that statement, it means just nothing ! When do you know that a loss is small enough to close that trade ? When do you know that a profit is big enough to take profits ?
My advice, spend your time building a system and confidence on it, without it, you are just losing your time, not only your account.
Science is a Means to an End. Means is Knowledge, End is Control.