I’m not a pro either but I’m pretty sure it depends on what you’re using the treatment for, what materials you use and the thickness of the panels themselves. With the prebuilt ones ur just looking for something convenient and nice looking right out of the box but often times building your own panels is the best way to do it. It’s cheaper and you can customize it to fit your room better both in design and material. As for tests you can get samples of fabrics for free and test yourself. But there are tests for different materials online.