I'm a big fan of any trade structure based on the VXX falling with a hedge to protect against big market downturns. So, I think if you backtest any trading model based on this premise over the last few years it's going to show really good results. You are selling VXX call credit spreads - which under "normal" market conditions will do well because the VXX tends to fall both when the VIX is falling and also when the VIX is relatively stable. Your hedge is selling the VIX put credit spread which will do very well if the market hits a downturn and VIX has a large spike. Fundamentally, I think this is quite similar to buying VXX put debit spreads or diagonals (Kim has done this a few times and you've likely read the thread on my weekly VXX put diagonals), and hedging with the SO VIX calendar strangle and/or buying OTM VXX calls or call debit spreads. I'm not saying that one strategy is better than the other, only that I'm a big believer in any trade structure based on a falling VXX over time (with some sort of hedge to protect somewhat against big market downturns).