I don't startch, size, wash or iron my fabric before using it. No trouble thus far and I've been quilting since the 70s.
I've never starched but did prewash all new fabric til about 15 years ago. I just found it easier to work with unwashed fabric. I never ironed fabric even when it had been washed and was wrinkled. I use templates or wide rulers to cut and they press it flat.