I try not to do but i still do. Because i am not a robot but a human. And sometimes panic cause selling in the beginning of a drop and can be useful as well 
Before I can say yes, I do panic selling especially when I see that the price was falling because I was afraid to lose my money. But now I dont do panic selling because Infound out that it was still increasing after the big dump of every coin. You only have to wait for it if you want to recover and get back your losses.