What has been occurring to me is that fasting cannot be one size fits all.
I would agree if you mean fasting length varies depending on the person and environment. But I would not extend this idea to adjust ‘water’ fasts with herbal teas and other fluids besides water.
Quantity does not out rule quality. You should refrain from supplementing if unable to prolong a longer fast. Why not pursue mini fasts in between cycles of healthy eating? There are health benefits from shorter fasts; it just takes longer.