I've left one sit for a day or two and didn't seem to have a problem. I think at some point, bacteria dies, that gives the other bacteria food to live on and reproduce and gives them some life. lol. They can be more resilient than people give them credit for. I know a few people on turtle forums that have a 150gal stock tub with like 3-4 canisters on it that drain the tub and clean and the filters with a hose with tap water and never have a problem with a cycle. Everyone's mileage will vary of course.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.
Sump Pimp #2
My Tanks and my shrimps