At the end of The Last Stand, Logan approaches Jean while her power is stripping flesh off him. His body keeps repairing the damage as he moves toward her.

At the end of The Last Stand, Logan approaches Jean while her power is stripping flesh off him. His body keeps repairing the damage as he moves toward her. That's a much bigger display than a wound closing after a fight. He's recovering while the attack is still happening, badly enough that we can see what she's doing to him. But he isn't reduced to absolutely nothing and then grown back. There is still a body there moving forward. So I wouldn't use this scene as proof that movie Wolverine can come back after complete destruction. I also wouldn't turn it into an exact measurement of Phoenix's maximum power. We have a specific confrontation, with Jean still in there, and a specific result. Logan survives long enough to reach her. That's already a hell of a feat without adding claims the scene doesn't test.