Many of us waste a lot of water through run off, especially on slopes. When watering on a slope if we put a lot of water down at once the water will run down to the bottom of the slope. The lower slope will be getting a lot of water through percolation and the top of the slope much less. When this has happened the plants at the bottom of the slope are probably being over watered and plants on top are getting under watered. Also a lot of water may have simply run off to the street, driveway or what ever is at the bottom of the slope.
We can reduce this problem by dividing watering times into cycles with shorter run times. For instance instead of watering for 10 minutes, water in cycles for three minutes. Set your controller to repeat cycles to be finished within a few hours.
There are additional benefits to this. You will develop deeper root systems allowing greater water and nutrient storage capacity for the plants resulting in watering less often and better slope stabilization due to the larger root systems.