I have learned to square up a lot as I sew pieces together. Simple blocks may not be as necessary if you are careful in your cutting and seam allowance sewing but blocks with angles need a lot of squaring up. It takes a little more time but I have found it worthwhile. I also have many different sizes of rulers to help in this process. Easier to square up a block if your ruler is the exact size ...i.e....3 1/2 " inch square and you have 120 to square up...LOL.