Between 12 and 24h body fluids are 100% saturated with liquid gases from compressed air blends. What does it mean? That there is not eternal limit of how duration of diving affects body physiology. After 12-24 hours underwater at depth risking in high saturation with liquid gasses there is iron limit of 3 days maximum that you need to have spare for decompression and 3 days is absolute maximum for any decompression. Aftet that there is not risk factor that extends time limit you have to obey. So it was somehow anticipated in 40s but finally after many experiments it has been confirmed that theoretical limits correspond to discovered phenomena during experiments.