I've been backtesting a strategy that requires a stop that is not tied to the key levels, or anything subjective, but something that also took the changing mkt conditions into the account so I was using ATR and it was pretty helpful. Good for algo and half-algo strategies in particular.
For example, one could set SL at 1 average ATR and take at 1.5 average ATR. Helps to quickly backtest something manually. Also, can be helpful in the usual trading as well. And I like the picture that was the result of the drawings as it helps understand how the market changes and how the same pair trades differently from what it's been like a year ago.
You can use this data to adjust your targets/sl in your trading.
TLDR: good volatility change tool, good for setting stops for algo backtesting.