Keeping your lawn at the same height throughout helps even out nutrients which ensures it has a uniform look. Also, waiting too long between mows stops the sun from getting into the undergrowth which may result in your grass dying from below. When your lawn is too tall, it may be difficult for the mower to cut even if you increase the blade height. This will make mowing your lawn that much harder. If your grass isn’t mowed frequently it will not be as healthy as a regularly mowed one. Finally, if your lawn is weak, it has more chance of being affected by diseases, pests and weeds.