an underlying can fall to a price that isn't listed as a strike price on the option chain for the expiration you're trading on. Therefore you couldn't have placed a butterfly spread there for the price to potentially pin. An example..AAPL stops offering strike below 105 for front-week. If it collapsed to $90...?
in conclusion, by definition, you still run the risk of it not pinning and going bust (in this ridiculous hypothetical)
Not exactly sure what you mean? AAPL has strikes listed many st.dev away from spot.
Are you talking more about the timing of the event? One can structure butterflies across the term-structure as well, not just ATMF.
