Well first let me say that I find nothing wrong with rolling into a Prego Fly. If the market is falling hard, for example, rolling a put spread down will cost money and still put you in harm's way. Rolling into the Prego Fly will require a small net debit compared to the capital at risk in the credit spread and if the market keeps moving lower, you could actually make some good money. On the other hand if the market quickly reverses you only take a small limited loss. So a Prego Fly adjustment is not something to be feared but simply a tool to use when needed to limit your risk and prevent taking a large loss.
Now in 9/11 I was not in any positions (thanks to workload at the time I was saved

). But in a 9/11 situation I would have skipped any adjustments due to the severity of the drop and simply rolled into a PREGO Fly or shorted futures and focused solely on limiting my losses. Again, a Prego Fly is just another means to limit risk so if the market is making a huge move, I have ti put it on without emotion. I will be safer and better off in the long run when the market makes such a large drop than trying to stay out in front of the train.
I have been doing OTM credit spreads for almost 3 years and I basically average about 2% a month which usually includes some small limited losses (i.e. I usually make 4-5% in most months and adjustments/limited losses smooth out the average.
Standard deviation is a tool I use through implied volatility since IV is one Sigma. If you take the ATM SPX straddle price, you are getting a representation of the Market Maker's pricing for a standard deviation move distribution in the market until expiration. I have said that a good shortcut method is to double that and use that range as a good starting point for strike selection. Of course one should not use this tool alone.
So SD is certainly a good guidance tool I would use along with support and resistance, trendlines and seasonal considerations, as well as fundamental analysis of what is going on in the market.
Quote from SteveJ:
Coach
It is reassuring to know that to date you have never had to use it.
Even in times of 9/11 and such it is good to know you were able to get away with just rolling down your spreads rather than pushing the little red PREGO panick button ;-)
How long have you been doing OTM credit spreads on the SPX for ?
From these OTM spreads what would be your monthly average return without getting to specific of course ?
Finally what are your thoughts on standard deviations as a tool? I tend to use these as a guideline for where I will write my shorts with success ?
Again love the thread 
Thanks again,
SteveJ