You "pay" points per day of your stay. If you are there on a Saturday, you pay what ever the Saturday points are. If you stay into a different season, you pay that seasons points for that day. The week listed in the charts are a example of a Sunday through Saturday stay.
The week listed on the chart is 7 consecutive nights within that season, doesn't matter which days of the week. There is no savings on the week points total, it's just there for convenience, 5 weeknights + 2 weekend nights.
If it overlaps, you cannot use the weekly total, you would have to add them up individually by date.