The deals are mainly very short term but also for very long term though not as cheap as short term.
3 months ago a Norwegian cruise ship itinerary was cancelled at last minute scheduled to go to Cuba, and we paid $100 for a 5 day cruise very short term notice price, plus port charges and tips of course.
When we lived in SoCal and near San Pedro, we were on the last-minute list for Princess. If you could could pick up and go in a couple of days sometimes the cost would be as little as $100/day.
They don’t make much money on us, though, as we don’t gamble or drink.