Recently, Wolverine’s healing factor has been shown to be far more powerful than many fans are familiar with.  It seems to me, though, that there’s a perfectly plausible explanation for why it’s so potent these days.

When Hulk returned from Sakaar, he was much stronger and more durable than when he left.  His strength and invulnerability built throughout his time on the planet because he was facing bigger, stronger, more damaging threats.  As he kept pushing his body to the limit to confront these new threats, his threshold rose.

I imagine the same thing has occurred with Wolverine.  He’s pushed his healing factor to the max at various points and, slowly, how far he can push it has extended.  It’s up to the point where only a time amount of DNA is needed to reconstruct the entire being.  It’s a bit excessive and probably unnecessary, but at least it’s potentially explainable.