My mother used to do this. She said she did it because of the poor quality of the material that was all they could get during the depression and the war years. That was done before the really great manufacturing processes were done here in the US. I really don't think you have to do it anymore. Most times the material comes straight from the looms, is treated with the fabric finishes, then folded, ironed, and wound onto the bolts for shipment. Never a human hand in the process. I really don't think this is necessary anymore. I never do it and I don't have problems.