Weeks that match what the client recorded.
Hours go in by day. The week is submitted, approved, and checked against the client's confirmation. Hours over the day's limit go into a bank and come back out on a short day, so the report is always whole.
Weeks end on the client's day, deadlines follow the client's clock, and periods are the client's periods. For a federal prime that is Saturday to Friday, noon Eastern, 4 and 5 week months.