It's worked very well for me. I primarily trade with $TNA and $TZA. However, I don't exit the entire position on RSI >70. I will sell 1/2 and use a trailing stop in case it continues to run. I have used this methodology with other etfs such as $NUGT, $UGAZ, $ERX, and $EDC.
This doesn't address your particular issue, but I also use Connor's strategies. However, I have chosen to use his technique of incremental buys with MOC orders once the RSI2 <15. I only trade leveraged ETFs.