Pretty sad.
For those who might court disaster by following any of what's transpired above:
• There is no direct mathematical relationship between delta and a P(ITM) finish, however,
• with a couple of not-too-wild simplifying assumptions, a useful parallel can be drawn. (There is at least one exposition on YouTube -- it might be MIT, but I can't say for sure.)
• Using delta as a stand-in for P(ITM) lets us use it as a single side to a two-sided distribution of market movement.
• If one were interested in a "10-delta" iron condor -- where the short strikes were chosen such that each side showed a |0.10| delta, that leaves the remaining 80% of expiration outcomes as your finish area -- you've lopped 10% off the top, and 10% off the bottom.
• Howsomeever! If a close approach brings fright (and a decision rule requires a response), then one must figure in a policy on P(touch) as well. P(touch) is quite complicated compared to the BSM probability-of-finish, but a consistently close approximation to P(touch) can be had by multiplying P(ITM) by two. This brings the range-of-trade-response in from both sides though, from ±40% out, to ±30% out. (Because again, your unacceptable range doubled, from the P(ITM) of 10% on each side, to the P(touch) 20% on each side.)
If you think that iron condors are automatically set-it-and-forget-it option set-ups, or you listen to some drooling fool who thinks that themselves, you will have Mr. Market mercilessly raping your ass before a year is out. That's a promise.

If you'd like to learn more, search on YouTube for "Choosing Confidence Intervals" or something close to that. Have fun. Be safe.
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