False.
Proper mowing frequency does not involve leaving two-thirds or more of the leaves. The recommended mowing height and frequency depend on the type of grass and the growing conditions. However, a general rule of thumb is to mow often enough to remove no more than one-third of the leaf blade at a time. This helps to maintain the health and vigor of the grass, as well as to prevent stress and damage. Mowing too low or infrequently can weaken the grass, making it more susceptible to diseases, pests, and environmental stressors.