Each child custody case is different because no two children and no two circumstances are exactly the same. One thing that parents have to remember is that they need to set the terms of the agreement based on what their children need now. This can be a challenge because we often like to plan ahead. We know that you might think that you want the parenting plan to last as long as possible, but that might not be what's best for your children.
As your children grow up, their needs change. What you come up with for a parenting plan for a newborn isn't going to be appropriate for a teenager. This is one of the reasons why there is the option for custody modifications. You can have the custody agreement adjusted to fit your child's needs, but this doesn't have to happen every few months.
One thing that makes the situation easier is if you and your ex can work together to do what is best for the children. The flexibility allows you to do what is necessary right then. For example, maybe your daughter is interested in dance, but she needs her father involved for all of the father/daughter dance numbers. This might mean that you have to switch weekends with your ex so that can happen, or you and your ex might both go to the venue to support your child.
We know that this is a challenge, but it is often possible for parents to work as a team to put the kids first. These situations don't have to be a constant fight between the adults.