Avoid sprinkling your lawn by hand as much as possible.  Why? It’s just a matter of uniformity.
Over a large surface area like your yard, it’s very difficult to determine if you’re equally applying the same amount of water. Most people simply don’t have the patience, time, or “eye” to adequately measure how much water is being applied across large areas. If you use an irrigation system, make sure water is reaching all parts of your lawn equally. Pay special attention to slopes and areas under and near trees.