Unilateral training definitely has value. Focusing on one side at a time forces the working side to call more muscle fibre into action because it doesn’t have the other limb helping to complete a movement. Though it is not the best approach to building overall strength, it is a great way to discover and fix weakness or imbalances in your musculature. To get the full impact of unilateral training, or to find out what it can do for your body, I recommend doing it exclusively for a few weeks. Just be prepared to spend a little longer at the gym, as you will be doubling your training time.