It's good to set targets with trailing stops.
I usually set a 10% Trailing stop to sell 20%-30% of my holdings. If it rebounds upwards on a signficant gain, I still have my 70-80%. If it drops another 10-30%, I look for reentry.
I use other trailing stops at other % of holdings to make sure I reduce risk and maximize return. It's a very good discipline to practice, even when my emotions are screaming SELL!!!! or HOLD!!!!
8 or 9 times out of 10, the discipline has really saved me.