I learned from my brother that on big farms you have to stagger your pivot irrigation, so each section of the field is watered in prime watering times. If the pivot waters on the same 24 hour cycle, and waters the same area of field at the same time every day, you will be able to see where the crop thrived in the cooler watering time and where it fell behind because it was watered in the hot hours of the afternoon and evaporated off. In larger field-like yards, It can be difficult to water your whole yard in the prime early morning time. Dividing these yards in halves or thirds, and watering every other day to every third day, will allow you to water each section in a prime time window. Most clocks have programs a,b,c,d which allows you to put half the yard on program A and the second half on program B. Then you can water program A on odd days and program B on even days allowing you to water more efficiently in those prime cooler hours of the day.