One thing we should also remember that because of the finite size of either silver halide particles in films or pixels in image sensors, it would not make sense to use very high F values - it would just not serve the purpose since once CoC is comparable with the size of the minimal light-sensitive particle/element, further increase in F will just reduce the amount of light without any increase in sharpness (e.g., a line which has the same width as the light-sensitive element would be recorded in the same way as a line which is only half as wide). For cameras with lenses that have very short focal length (such as, e.g., mobile phone cameras) pretty much everything is in focus (beyond a few dozen cm) even at low F (if you can control it, that is) - just because CoC diameter is so small it is comparable with pixel's dimensions of the image sensor. They are, in effect, "permanent focus" cameras.