I do not understand how you can possibly lose more than everything you have ever made in a structure like below, if you can find high probability setups.
Very simple: Let's say you make $2K on each vertical spread that you sell. You have sold 5 vertical spreads and have made $10K, very good. A "rogue wave" hits, you get assigned, the spread between the short and the long leg is exactly 5, multiply that by 20 contracts that you did, $10K gone!! Boom!!! There you go. Profit back to $0!!! If you only 0.5% risk per trade, you are not going to make much money, only 0.5% return. And when the gamma starts accelerating, you are not going to be facing just 1% slippage, the bid/ask spread will widen as well as the spread between the strikes between the short and the long legs so you end up not able to sell the long legs as much as to compensate the losses from buying back the short leg. That is if you are hedged in the form of a spread. If you sold naked, then you just die like James Cordier.