For what it’s worth Michael B, I understand what you’re suggesting regarding this test method possibly being invalid/misleading for super lightweight fabrics, and whether small defects in the material affect real-world weather resistance as much as tested HH values. Much of your speculation rings true in my opinion and is at least worth consideration.
The only way to really test your hypothesis at this point is to make some shelters out of the suspect material and see how they hold up to some heavy rainfall. I can understand why a MYOG enthusiast might not want to do that, only to end up with a shelter actually isn’t adequately waterproof. Someone (not me) must undertake this endeavor for the glory of scientific discovery!
