Shared parenting provides a framework for effective co-parenting. Distance between the homes of each parent. Ability to maintain consistency in children's bedtime, homework responsibility, etc.
Most children do better with a fixed schedule so that they can plan ahead.
Fixed does not mean rigid. Children feel defeated with rigidity, whereas appropriate flexibility gives them a sense of their own self-worth and control over their lives. Parents who allow appropriate flexibility in schedules help their chldren develop a sense of control over their lives and a sense of being important.