Divorce and child arrangements

What is a typical set of arrangements for a child when their parents divorce or separate?

It is presumed (unless the contrary is shown) that it is best for the child for both parents to continue to be involved in their life. Beyond this, there is no 'typical set' way to handle divorce and child arrangements.  
It is for the parents to ideally agree what arrangement would work best for their children, and for them (see Do I have to go to court to decide where my children will live after divorce or separation).  

If it needs to be decided by the court or an arbitrator, the decision will be made depending on what the judge or arbitrator considers is in the best interests of the child (see How does a court decide living arrangements for children after divorce or separation?).

The focus will very much be on the particular child, and what routine is both best and manageable for them. There will be a great deal of focus on practical considerations, i.e. what is a child's routine throughout the week and how well can that mesh, practically, with each parent's commitments? It may be, for example, that one or both parents are in the (not unusual) position of balancing family life and evening work commitments and that they can be home on certain evenings and not others, or that one or both parents sometimes travel for work. 

The court will work 'bottom up' from the various family members' schedules and will resist attempts to work 'top down' from general labels which a parent might be tempted to apply to the day-to-day care arrangements such as 'primary carer' or from a parent's desire to parent a child for a given percentage of the time. There are therefore as many possible sets of arrangements for a child after their parents divorce as there are children and family routines.