Exactly. Every investor should or trader should have a clear plan of action in case of unpredictable events in the market. If a panic sale begins, you should have a strategy for how you will act and what to do.
Even with such a plan, it is not always possible to take advantage of the situation. The market is sometimes unpredictable, and it is easy to make a mistake during panic sales.
Panic selling causes more pressure on market and emotions drain the energy of market with help of downtrend. Mistakes are expected during price flash-crash and traders act on their ability in order to avoid loss.