How is multi-days (2 before I chuck mine in the wash; and I hang them to dry in between wearings) any worse than the 97 degree humid summer heat and nearly 15 hours of consistent riding I spent doing a double last summer?

I haven't run into any issues from either situation. 30 mile round trip to work, and I go 2 days between washing shorts and jerseys. I routinely spend 7 to 12 hour days for long rides, and I don't bring a clean pair of shorts to change into. (Although, if I go for a 600k next year I'll bring a fresh pair of shorts to change around the midway point.)