See VERGO VERSUS SMOKER, in the chapter where LAW recovers his heart and cuts down VERGO, VERGO didn't need to erase SMOKER to say he beat him, SMOKER was incapacitated and exhausted.
Here is the chapter.
SMOKER doesn't necessarily need to be knocked out to be defeated, note the similarity with what KAIDO did to LAW, he is exhausted and on the ground, VERGO won, just like KAIDO beat LAW and ZORO.
I understand the topic, you talk about recovery, but I don't think the region in which KAIDO hit LAW has reached any vital point, for example the head is extremely sensitive, LAW could need urgent treatment if it was hit in this region.
Being able to fight X wounds is not uncommon, see Luffy versus Katakuri, or INU and NEKO who survived 1 full night of torture and limbless.
The real thing is that the plot is still covering LAW.