The 24-to-48-hour figure is not a guarantee of visible mold, but the start of colonization. In a warm, humid Kansas City basement the process runs faster; in a cool, well-ventilated space it can be slower. Either way, the clock starts the moment materials get wet, not the moment you notice a smell or a stain.
The reason drying beats cleaning is simple: mold feeds on trapped moisture inside wall cavities, subfloor, and insulation. Wiping the surface does nothing about the water behind it. IICRC S500 drying uses commercial dehumidifiers and air movers, verified with moisture meters, to pull that moisture out before mold can establish.
If mold has already started, it becomes a remediation job rather than a drying job - containment, HEPA filtration, removal of contaminated porous material, and a moisture fix so it cannot return.