I wouldn't use squares for my nine patch smaller than five inches. Once it is cut that square in the centre is just too small. The best D9P quilts always seem to have the darkest solid colour in the centre position. A black, dark green or purple seems to work well for me. My focus fabric which will be the uncut squares is always on the corners and then I look for a more subdued small print or marble that will end up as rectangles. This works well for me even if you do it scrappy.