One great thing about setting up a parenting plan with your co-parent is the predictability it brings. For example, there should rarely be a question about who pays what and when one parent has the child(ren). This stability is a huge stress reliever for children and parents alike. That said, life circumstances change. Little by little, your life may have transformed so much that seven years later, it is a poor match for the official parenting plan.
Some divorcing couples with kids are able to arrange custody and parenting time schedules that best fit their circumstances with little to no disagreement.