With a "new" village there is a chance of losing all your villagers over night. As squawky has said, once you get your village to a point where they are self sufficient, you can keep it on 2x for several days and they will be fine. On easy once you have level two harvesting you should be ok just over night. On hard, they might make it over night with only level two harvesting, but there is still a good chance you will lose them all.
_________________________
The VI