Mine have been "off" on every quilt I've made. (I'm tackling #13 now.) But they do get better and better each time. I'm not sure there is an exact answer to solve the problem. More likely, I think I am getting more precise in cutting, better at keeping a consistent 1/4" seam allowance, better at easing in excess fabric when necessary, etc.

By the way, I don't pin a thing. I'm lazy that way. It takes so much time and I get the same results whether I pin or don't pin. I'm sure it's a personal preference. But I'm really getting good at matching points without pinning. Like everything else, it just takes time and practice.