Training your legs will boost your Full Body muscle growth - so ensure you're getting sufficient squat time in your program. "Training legs should be THE most important part of your training program, no matter what is your goal. Leg day is must.
Working legs can help correct muscle imbalances and aid in injury recovery. Adding leg workout to your routine allows you to focus on muscle groups that get underworked and neglected during your daily life, sports, or other exercises. Strengthening these muscles can help you to prevent imbalances.