Such is the nature of reversion trading strategies, you make $ 8/10 but the other 2 times you lose most if not more of what you make. Commodity pits are littered with stories of traders doing these spreads. I personaly clerked for an oil trader who went through the cycle at least three times doing reversion strategies in the crack spreads. Not for the faint of heart and definitely not less risky than straight up trading, as some pro firms might want you to believe. Good luck