How would you address the challenge of maintaining individuality within the structured roles of a monarchical family?

In classical monarchism, the main issue in sequential family heirs is the assurance of the quality of their ruling. A check system much like USA's check system that is just as powerful as the monarch and their family should be in place. Each person, whether royal or not, make mistakes and have their own unique dreams wants and ambitions, losing those ambitions and wants is something often required of an heir, and when you lose your individuality, you lose drive, and subsequently the ability to confidently lead. Heirs should not be required to hold their office, but may be required to find a suitable replacement alongside a checking force.