I was just thinking about the painful recovery period I went through last summer following a major surgery and thought "How effective is healing in the art of waterbending?" We've seen it used to treat internal injuries such as the burns and neuromuscular damage from improperly executed lightning redirection, surface level burns from firebending, and even used in a manner similar to TMS therapy to deal with psychological trauma.
But we also know that it has its limits.
Katara couldn't save Jet after Long Feng effectively caused him to die of what I can only imagine to be internal bleeding via a rock to the chest at vehicular collision speeds and possible organ penetration if his sternum fragmented and punctured his vital organs. Katara was already a master healer in her own right and she still couldn't stop major internal injuries.
We do know that healing used with spirit water from the spirit oasis at the North Pole has special properties and allowed Katara to resurrect Aang after Azula killed him with lightning, albeit with Aang having to spend the better part of the next month in a coma reestablishing his connection to the Avatar Spirit. But it can bring back the very recently deceased. I assume it had to have been less than seven minutes since it takes roughly that long for the brain to die of cerebral hypoxia.
But what are your thoughts? What do you think are the upper limits of what healing via waterbending can achieve with and/or without spirit oasis water?