Cultivators, as they advanced, could go without food, water, and sleep in greater lengths of time than before. Mortals needed 3 meals a day with a solid third of day spent asleep as bare minimum for good health. A World Realm at the Iron Tier could go for a year without any negative consequences.
Unfortunately, that endurance applied to battle as well.
If Lind went into battle and had precise control and was able to keep himself whole, he could go for a year easily with the timing of elixirs before he had to stop and recover with rest and possibly food.
The level of the aether beasts felt close to Delenn and he had never ever caught her asleep or eating unless he offered her food ever. In fact, her bed was clean but clearly unused for centuries based on his Eyes.
