I am having the same issue myself and it all has to do money management and the trader and the trade itself. because everyone trades and think and feels different. So no one answer fits all, but its a great discussion.
So here is what I decided to do.
1. Open my plan book and write a section called Monitoring the Trade if up by $200 (i trade the es future and $200 is half of what I intend to make on the trade)
2. I there I wrote how I plan to monitor the trade and adjust the stoploss at this potential profit. The concern, is what happen if price come back to my entry or above the $200.
And so on and so on.
Because everyone has there own way of managing the trade. Some breakeven, some breakeven, some do nothing, some that half profits, etc. etc.
I will test the money managment that I believe will work for me and my logical and for each trade record the data for my plan, and what others suggestion. After about 500 trades, I will then have EMPIRICAL DATA for what works best for my trading business.
But its great that ET experienced traders are sharing their knowledge.