A while ago I asked for advice and hints about accurate cutting and seaming. We had a great discussion and I learned many things. I followed all the advice, cut a bit more generously, aimed for a scant quarter inch seam, and I am very happy with the results. I finished my baby quilt top, and all the squares are exactly 5 inches, and the top measures exactly 49 inches!
Here's a link to my finished top, not the best picture, the colors are a bit brighter than they look. Thank you all for your help.