The same plant in clay soil would have access to about two inches of water. So it wouldn't start to feel drought stress until after four days. It's not quite as simple as that, of course. South Georgia doesn't have soil that's all sand, and north Georgia doesn't have soil that's all clay, and the exact water-holding capacity of your soil depends on its exact makeup. Adding organic matter to any soil enables it to hold more water, too.
Soil amendments do other things, but mainly they increase the soil's water-holding capacity.
After heavy rains the soil in your yard or garden may be saturated. All the pore spaces in the soil are filled with water. That's not the true water-holding capacity of the soil. The field capacity of the soil is the amount of water it will hold after gravity has pulled off that excess water. It may take a day or two after very heavy rains for the excess water to drain off.