You make sure you keep enough in the freezer to maintain temp. just like the old "ice boxes did" !!!!
BTW:
Before Irene hit, I put about a dozen half gallon jugs of water in the freezer for a little insurance. I left them there. When I lost power for 6.5 days in the Halloween snow storm/power outage, all was just fine. Some things on the top shelf had barely started to soften and I bet I could have gone nearly another week on such things as frozen 1/2 gal. jugs.
FWIW
Lee