Interestingly, the second thread on this topic today. Here's my perspective on squaring quilt tops. I square up each element of a block as I go along. Square up each block as it's completed. Even when chain sewing, I still press/square up at each step. It's unlikely, at that point, that your top will not be square. When measuring for borders, I measure the center length and width. Ease or stretch as needed. My quilts are certainly square enough after this (to within a 1/8" measurement and who is going to notice that!) After sandwiching, I will trim off major excess of backing/batting to within about 4" of the quilt top. I hand quilt so I'm sure my distortion is less than those that machine quilt so that may be a factor. Once the quilting is finished, I sew on my binding strip to the front lining up raw binding edge to the edge of the top. Sew with 1/4" seam. I then trim the excess backing/batting to 1/2" from biding seam. I have never cut off my binding doing this. I then proceed to hand sew my binding to the back of the quilt.