Custody and visitation arrangements vary from family situation to family situation and can be tailor-made to maximize suitability. The parents can agree in advance on which of them the child/ren will live with and how much the other parent will see them and where. They can  work out a personal  package in the form of a written agreement, and ask the court to authorize it. Failing this, one, or both parents, will sue for custody, and the court will decide.