I live in the San Fernando Valley, California. Some years, the temperature rises to 117 F - pretty darned hot. At that temperature our one wall air conditioner shuts off.
I haven't stored XS strips in the refrigerator, and they still worked fine.
(Years ago, I used ProTime for INR testing. These REQUIRED refrigeration -- they were shipped in a foam container packed with gels that kept them cold. They went from the shipping container into the refrigerator.)
I don't recall having to refrigerate the InRatio (a dangerous meter) strips. Coag-Sense strips don't require refrigeration (at least, not at usual room temperatures), and I haven't had problems with XS.
Sometimes it's easy to apply old information from other products to entirely different products.