Put a can, or any container with an open top and straight sides, on the ground near the plant and run your sprinkler for ten minutes. Then measure the water in the can. If it is half an inch deep the you need to run the sprinklers for twenty minutes to deliver an inch of water. That remains true no matter what kind of soil, what the temterature is, or the time of day.
"A significant portion of the water will be taken up by the dirt away from the plant."
This is a nonsensical statement. The dirt will take up all of the water, and the plant will then take up the water from the dirt. That is the way horticulture works. Other than bromeliads, which don't have roots, plants take water only through their roots, and they take it from the surrounding soil. They will send roots outward and downward to find moisture in soil that is distand from them.
Regardless of the area, type of soil, temperature and humidity, soil moisture is lost only by being taken up by plants and by drainage. Essentially no soil moisture is lost to evaporation; only a tiny portion of moisture from the top 1/16th inch or so. Tight clay soils can remain moist below the surface for a couple of weeks after a significant rain because they do not drain. Very sandy soil will dry quickly because the water drains quickly.
IDemo: yes, that form of watering instruction is far more useful.
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