Depends in what specialty the nurse works in. I've been a nurse for 25 years and there have been occasions nurses are sent home due to low patient census.
Surgical floors may see a decline during holiday time due to people not scheduling elective surgery, but a medical or cardiac floor may see an increase due to stress, holiday eating patterns causing disorders to flare up, and unfortunately, family members that admit "grandma" to the hospital with vague symptons just to get a holiday from caring for her themselves. So it usually balances out to where the areas of low census send their staff, called "floating" to the floors that need more nurses due to high census.
I did travel nursing and went to Florida for the winter where the influx of snow-birds increased the census, but if a hurricaine was brewing and headed toward that particular town, census would drop as people left instead of staying for their pre-scheduled orthopedic surgery. For budget reasons, they would not just divide the remaining patients amongst the nurses, each nurse:patient ratio would need to remain as close to norm, which means nurses go without their hours.
I am now in home care, and if one of the clients is hospitalized, we have to call the nurse to cancel their shift, as obviously there isn't a shift to go to.