Both ways work. It comes down to a personal preference. I will precut my long strips for the borders before I start cutting any material for blocks so that I don't have seams, if I can. But if I have to, because I am sewing from a kit, then I don't sweat the small stuff, and just have seams in the borders. I don't know about anyone else, but I do try not to have the seams in the center of the border. I try to offset them and stagger them around the quilt.