I am working on my tote bag but I thought I would just point out another reason why we use that extra fabric on the back of our stitching. It isn't just to keep things firmer and hide the threads from behind - it also hides the yellow felt pen that makes its way onto your stitching when you are babysitting a 2 year old.
Luckily the yellow part doesn't show through the main stitching and the blob on the back will probably fit into the seam. Or I could wash it but it depends on how close to the deadline I get with the bag. I'm not aiming for a pass yet, I might need it later.