Water is the most important factor in a beautiful lush lawn. Oftentimes, sprinkler coverage isn't correct. Check for head-to-head coverage. The heads are most effective when one sprays all the way to the other. Plenty of water is important when it gets hot. Use a shovel to open the ground to see if the soil is moist six inches down. I usually check a green spot on the lawn and compare it to the dry spot. It is easy to be fooled; the top inch can be wet while it's dry as a bone a few inches below. I regularly get the questions of how much to water and how often. The best way to water a lawn is heavy, but infrequently. Watering every day will lead to shallow roots and a lawn that can be stressed very easily. Train your roots down by deep soaking. If the water pools on your lawn, you may need to get an aeration or to set up multiple short waterings to get the water to soak in better. Another point is your water start-time. Most people like to run their sprinklers between 2am and 8am. I would avoid this time. Often subdivisions over-develop and you my have pressure issues. Sprinklers don't work under low pressure and you can get dry spots that don't make sense. Also, if you can watch your heads to make sure the pressure is good, I would recommend it. Watering in the middle of the day? It is a myth that you will burn your lawn if you water in the middle of the day. Watering in the middle of the day does waste water in losing it to evaporation, though, so I would advise watering in the late afternoon or late morning. Night watering is also frowned upon by many. Yes, you can set yourself up for fungus, but if you water deep enough and let the top dry out, you should be fine. Whatever you do, never let the water puddle; this will burn lawns anytime of the day.