I entered a one year collar hedge on QQQ in early July because the top was in. Basically locked in 10% downside and 15% upside limits for a year.
The last couple of days' volatility has been a great lesson about gamma. Gamma is the rate of change in an option's delta as the stock's market price moves closer to or further away from the option's strike price. Delta is the amount of change, in cents, that an option will make in response to a $1 change in the stock.
I.e. As the share price falls closer to my long put, the put becomes increasingly sensitive to the share price. Thus the combined position acts like a spring that offers increasing resistance to falling further, even if my QQQ shares are falling hard.
This is how my whole QQQ portfolio, which even includes some unhedged positions, is down just over a third as much as the stock is down today.
Vega - an option's sensitivity to a change in volatility - has been helping too. I'll give up some vega gains as things settle down.
TL;DR: I hedged at the top, because it was in. It worked out well and I lost tens of thousands less than I'd otherwise have lost. Thorsach haters can cry over their portfolios today.