I had been told when first starting not to back stitch, because of old frog, ribbit ribbit, but found when putting my blocks together sometimes seams would come apart and then you have a problem. So have really paid attention to what others said. One lady on Alex Anderson said to make first two or three stitches smaller and stops that, another said to back stitch two or three. But if you are chain stitching, to back stitch at beginning and end of block can be daunting. I like the idea of leaving thread longer, that might work and I am going to try that, thank you. But to me whatever works is best. I found that if you do have to rip it out two or three stitches that are back stitched do not cause a problem. My problem is remembering to back stitch beginning and end of block. I found whatever you start out with and it becomes a habit is hard to break, if I had started out back stitching, I may not have a forgetful problem ha ha. Hope this helps you..
Rita