Parents who after divorce or separation get along, who have common goals for their child, who don't fight and want their child to spend relatively equal amounts of time with both parents will often have shared parenting, which is the highest level of joint custody.
Joint custody for most parents does not mean equal time with the child, rather one parent is the primary residential parent and the other parent has a schedule of parenting time which might be alternate weekends, midweek dinner visit and the sharing of holidays on an odd/even year rotation.
Parents who have shared parenting may have a schedule that the child spends one week with the mother and the next week with the father throughout the year. Sometimes the schedule is to split the week in half and then flip the week the following week so that neither parent always has the weekends. The holidays are still rotated however the summer recess is shared equally.
For shared parenting to work well, ideally, the parents should live near each other so that when the child goes to school the travel time to and from school to each parent is not too long. Parents who have shared parenting need to be committed to making it work because the judges will not order shared parenting unless both parents want it. If the parents can't agree to shared parenting the judge will not impose it. In fact, many judges think it is disruptive to the child and would rather provide for sharing the summer recess but not the school week unless the parents are in agreement.
Child support payments are also affected by a shared parenting arrangement because clearly both parents have to maintain a home, clothing, provide food, entertainment and activities for the child on a daily or weekly basis. In NY the child support laws do not automatically adjust child support because of shared parenting. If the parents have significantly different incomes, the parent with the higher income will usually pay child support, however a reduction from the usual amount is often negotiated.