Wolverine heals fast, but the older stories don't treat that as a reason for every injury to be over immediately.

Wolverine heals fast, but the older stories don't treat that as a reason for every injury to be over immediately. He gets hurt. He gets poisoned. He gets worn down. Sometimes he needs enough time for his body to catch up with what has been done to it, and sometimes he needs somebody else to help him get that time. X-Men #116 gives an early example when a creature bites his hand in the Savage Land. He explains that he heals quickly. It's a pretty simple demonstration compared with what comes later, but it shows the basic point: something hurts him, and his body repairs the damage. The more interesting cases are the ones where that process becomes a problem. What if somebody keeps attacking? What if there's a Brood embryo inside him? What if he's so badly injured that getting away by himself is already too much? Those things happen, and the answers aren't all the same. Looking at the actual situations gives you a better idea of what the healing factor is doing than just assuming he'll recover from anything, as fast as he needs to.