The one third rule.

Cutting only one-third of the grass height at a time is key to a healthy lawn. This method helps the grass recover and grow better.
Removing more than one-third can stress the plants, leading to weaker growth and making them more susceptible to pests and diseases. It can also cause scalping, which exposes the soil and roots to sunlight, damaging them and promoting weeds.
Following the one-third rule encourages deeper root growth, improves drought resistance, and results in a fuller, healthier lawn. This practice also keeps the grass greener since the remaining blades continue to absorb sunlight, providing necessary nutrients. Overall, sticking to this guideline is essential for a healthy and long-lasting lawn.