While custody and visitation are closely related, they are actually two separate issues. It can often take parents quite some time to come to an agreement on custody, and many times, these matters have to be resolved by the family court judge. However, even once legal and physical custody is determined, there is still the matter of visitation.
Visitation is an issue that must be addressed in your parenting plan, and that is true whether you have a sole or joint custody arrangement. The best case scenario is that the parents are able to come to an agreement about what the parenting time schedule should be, and that is put into the parenting plan and then approved by the judge. However, this doesn't always work.
In cases where the parents are unable to agree on a visitation or parenting time schedule, the first step is usually to attempt a formal mediation process. Even when parents are not able to agree on their own, the addition of lawyers and a mediator to the process can help them begin to see the need to compromise. If the mediation works out, the plan is approved by the judge and put into a court order. If not, the case proceeds to court.
In this situation, the most common scenario is for both parents to come up with what they believe is a fair parenting time schedule with the help of their attorneys. Each then submits their plan to the court. The judge then reviews the plans and makes a decision on what the court believe is in the best interests of the children.
Source: Tennessee State Courts, "Parents' questions," accessed March 11, 2016