Well, a two-bath for fiber prints is still better. The idea is for the first bath to dissolve the silver, and the second is to remove it from the fiber base. The actual fixing happens pretty fast, and I have had no problem with 2 30-second baths. The Toning Book says a single bath fix can contain up to .5g silver before fixing is impaired; with two-baths it can contain 2g. With TF-4 or the Flexicolor, that sounds conservative because those baths seem to last forever.