On MY South Carolina lawn, I water on MWF and SAT. Sandy soil is like rain on a tin roof--inthat it drains so fast that the roots do not get a chance to absorb any moisture. I know that watering this often leaches the soil of fertilize. But the difference is a dead lawn or adding extra fertilizer to compensate for the leaching. As Ric stated, adding SOM to increase the water retention is a great way slow down the leaching. I have truck loads of SOM delivered and I sprinkle it over the lawn in the winter and the spring green-up works upwards to the light. Clay soils are like rain on pavement--it puddles and runs off. However, eventually it will settle into the soil after many weeks. Around Myrtle Beach, SC there are in excess of 100 golf courses. I see their rotors wetting the greens at night (3:00AM or so). I've been told that watering at night increases fungus (?) but it does allow the water to penetrate the turf and not be evaporated quickly as during the early morning. I'm still debating that one. So in the end, watering often and long may be a practice for those with shallow wells. Watering deep and less often in sandy soils knowing that the water is not going to be there in a few hours tells me that the turf roots did not get a chance to take in moisture versus, watering deep and often to allow the roots to take in moisture and leaching available nutrients is a dilemma. To have a beautiful lawn is costly on the coast....so I pay a few dollars for a little extra fertilize about every 6 weeks on Centipede grass which likes poor soil anyway. On the St. Augustine, I fertilize lightly with 15-0-15 every 4 weeks in the summer until August. Now for the biggest problem--Those no grass hurricane ditches????????No water, No SOM, pure sand, too much sun....Bermuda grass or even crab grass???