I have never had a need to zigzag the binding edges together. My binding never puckers. However, I do starch the binding fabric heavily before cutting into strips -- whether doing straight grain binding or bias binding. Bias binding will definitely have more of a tendency to pucker (from stretching while you are handling it), so it is especially important to starch that yardage before cutting. My starching method is to mix a 1:1 solution fo Sta-Flo liquid laundry starch and water, "paint" this onto the yardage until the fabric is saturated, toss in dryer, then iron with steam. This results in a very heavy starch that stabilizes the fabric so it does not stretch while sewing. (I do the same for quilt backings to prevent puckers while machine quilting.)