Rainbow after a rainfall to water lawn

Answer: If you want strong grass roots that will grow healthy grass blades you need to be watering your lawn for a long time once or twice a week. Not short 20 minute spurts every day. Daily watering will likely lead to moss growing in areas that get a lot of shade. The ground never gets a chance to dry out. With daily watering your grass roots will stay short, because they do not need to grow deep roots to search for water.
For most lawns lots of water once or twice a week during the hot summers months is good but that is 3 or 4 hours with the sprinklers on. Yes, water is expensive, but so is repairing a lawn. It is more manageable and more likely to get done if all you have to do is pull out a hose and sprinkler once a week.
If you have very sandy soil under the lawn possibility a few times a week will be required.