A couple of notes. First, they have started shipping on Saturdays in some areas, or at least are trialing it. Second, we tried to come up with an optimal protocol as well (though for the three at at time plan), but actually nothing seems to maximize the number of discs as much as watching them the day they arrive and sending them back the next morning before the mail is picked up.You need to learn to "work the system" to get the maximum use out of it. They don't ship on Saturdays, so what I did on the 2-time plan was:
Receive New Movie: Tuesday, Wednesday, Friday, Saturday
Ship Movie Back: Wed Morn, Thur Morn, Sat Morn, Mon Morn
Also, even with the three at a time plan, Memorial Day, Independence Day and Labor day mess with the system.