Insulated glazing - Wikipedia, the free encyclopedia
"Typically, most sealed units achieve maximum insulating values using a gas space of between 5/8 to 3/4”
I would expect the double width screen hack would be between 1/2" to 3/4",
depending on the hardware. If it was only 1/4", it would still help,
but the gain might not be worth the price of the extra frame.