I think the answer to your question depends on how accurately your quilt is pieced before you add the borders. Is it even already? If so and you just cut your strips, sew them accurately and trim, it shouldn't be a problem. But if you are like me, somehow my center almost always is about a quarter inch smaller- have no eartly idea why lol. So I cut strips lOnger than I think I need and then smooth my quilt flat and lay that strip down the middle and cut to size. Then Do the same thing for the top and bottom after adding the sides. I learned this from Bonnie Hunter and now I almost always end up with a truly squared quilt lol. I never had wavy borders per we using the method you describe but definitely my quilts weren't all even which depends on the purpose of the quilt, a quarter inch difference won't be that noticeable anyway unless you are folding the quilt hehe.