I believe the concept of "止损" comes from big financial institution. It is a kind of strategy.
Look at the trend of each stock during 1 year period.
1) How many time slots will trigger 10% "止损"?I believe around 10 to 15 times.
2) How many time slots will trigger over 20% "止损" which is where the sense of 止损 or the profit/cutting loss is? No more than 5 times.
If small investor use automatic 止损 sell, in most of chances, he will lose chances to people benefiting from balanced market.
So 止损 is more like a concept of MM than a practical tactic for small investor less than 100K investment.