If I have a stock opening stock short, I'll keep it if it adjusted down, and then set a Limit Order for a certain additional drop in price. Usually stocks that adjust around $100 are good for a MINIMUM 5-6 point additional drop after adjust... If they are priced $300 or so after adjust, I figure they are worth another 15+ points drop after adjusts.
As an example...I held Iron Man short at $388, and I've kept the short...and it's dropped 80-90 points since then.... but NOT all stocks do that.
Again, I use them mostly at adjusts to earn additional $$...as I look at what profit I would be satisfied with for a Limit Order, then set it, and let it go from there.
Occasionally, I use them on bonds too...although I haven't been playing bonds as much any more with my huge port...movie stocks interest me more.
That's my 4 cents for you.