Hi Sandy,
Its all decision from client side how they want to design it. You can assign cost center(s) to profit center(s) in either 1:1 or N:1 relationship.
CCs are used to track cost, where as PCs are used to track both exp and revenue. So, it should be designed in such a way that how they management wants to get their desired results.
BR, Srinivas Salpala