Most wells have an intermediate tank, pressurized with a bladder. As water from the well is drawn, the tank fills until it reaches a certain pressure. Water is drawn from the tank. The tank has a pressure switch that turns on the well pump on demand until the tank has reached its maximum pressure. It stays off as long as the pressure doesn't drop below a set point. My well turns on when the pressure in the tank is at 20 PSI and off at 40 PSI.

Your irrigation system is on a timer, not the well, normally.

HTH

Scott