Check out the Coronavirus Crash on the Nasdaq Daily...
If you were to have rode this up from the daily breakout, you can can see the daily movement of each candle. As soon as I know the daily candle is falling below the 50MA I'm closing my position and locking in the profit. Then I'll wait and see where the market goes from there.
Individual stocks can bottom out like they didn't exist, but established indexes and ETFs like the Nasdaq for example, are not so easily tripped over.