Cutting a lawn too often, particularly with the blade set low, exposes the lower portion of grass leaves to bright sun, burning them. If this happens repeatedly, grass reacts by developing shallow roots. Shallow-rooted lawns are particularly prone to disease and weed problems. In addition, poor rooting does not provide enough nutrients to the grass leaves. A lawn with shallow roots may eventually die out.
Early evening is the best time to mow.
The late start gives grass blades time to recover before they're exposed to daytime heat and wind. Mow with a sharp blade, and never mow wet grass. It's actually best to mow your lawn in different directions. That keeps grass from developing permanent ridges, ruts or becoming compacted from constant traffic. Thatch appears right at the soil surface and looks like a layer of straw.