I would think check outs for sunday because most people fly and they have to have that saturday night stay for the low fares, check ins I would think would be either monday or sat.
When we went in July to CBR, we checked in on Sunday afternoon and it was a breeze. However, when we went to DL, we checked in on Saturday afternoon and although checkin was fine, we had to wait a couple hours for our baggage to get to the room.