I don't starch any of the fabric I piece, actually I don't prewash either.......when I read starch until stiff like paper, makes my piecing so precise .......I wonder if the piecing would be just as good without the starching, maybe just because the person is just improving on sewing skills...
I have been quilting for over 20 yrs......love the feel of the fabric, don't want to sew paper........and my seams, points, y seams, curves are matching, but it takes accuracy in cutting and matching and slow sewing to get that, not starch!