The simpler a physical operation or technology seems to be, the closer I’ll be to worrying about material properties.
Every physical thing eventually goes back to a natural material. Even “synthetic” materials such as plastics, nylon, or viscose, eventually come from a natural material. And natural materials vary.
Whether a natural variance will affect the end use is often hard to predict. A few years ago Consumer Reports took a close look at gluten-free foods and found that one of the hidden dangers was arsenic poisoning. Many gluten-free foods contain rice flour. Rice is grown in different areas with different soils; and rice has a tendency to absorb arsenic from the soil (if the soil has arsenic; some soils don’t).
I used rice as an example, but every other natural material has equally unexpected variances somewhere. When I buy a good such as quilting cotton, there’s an unseen army of people I’m depending on. Someone grew the cotton, harvested it, processed it, and spun it into thread. Someone else took that thread and wove cloth out of it at a set width and tightness of fabric. And then someone after that dyed or printed the cloth.
The further I go back in any chain of assembly or manufacture or processing, the closer I’ll be to taking a very close look at physical properties in the material itself. If I have to do that, then I’ll probably start learning about how to specify those properties when buying, and how to test for those properties, and how often I’ll need to test.
The simpler it is, the closer I need to look at everything.