Smaller delta strangles carry a much higher POP but they are prone to more outlier risk as a multiple of how much premium they carry. Since the outliers on a 5∆ strangle tend to be so much more severe as a multiple of credit than higher delta strangles, it becomes nearly impossible to size up… so even though you get a much smaller credit, each dollar in credit you receive could be exposed to more than twice the outlier risk than each dollar in credit of a larger delta strangle. Currently, a 5∆ strangle in SPY is trading for around $2.00 and a 25∆ strangle at $12.00 (in June). If you wanted to trade six 5∆ strangles to get the same premium as the 25∆ but with the higher POP, you would actually be carrying more than twice the total outlier risk than just selling one 25∆ strangle.