I have reduced my gross exposure over the past week after my portfolio has had an impressive run. A mistake I used to make was to keep large positions after I made large profits, even if I did not have strong convictions. This almost always led to giving back a nice chunk of profits.
I have read many trading books that say to raise positions when one is doing well. That does not work for me. I am able to think with a much clearer head when I have smaller positions. There are no hard and fast rules to trading. Like swinging a baseball bat, everyone must find the style that suits them.