It has honestly never occurred to me to do differently . I separate my wash into light colours, whites and darks and change all bedding weekly and towels often but never separate kitchen or bsthroom towels or even cloths that we've used to clean the floor from anything else and wash all at 30. Just reading other threads where people seem to wash at 90 and wondering . Disclaimer : we don't use flannels ! Also been doing it this way for 23 yes and no one ill or dead from it