When I saw '10,000 knocks' I wondered where the figure came from (drawn from the 10,000 hours to become an expert at one skill, perhaps?). But, broken down, it does not seem quite so exaggerated - if you say 1 mallet strike per second, this gives 60 per minute; 3,600 per hour.
So 10,000 knocks, which sound s a lot, is only around three hours work.
Admittedly, if this was done in one session your arm may be a tittle jaded.
I agree with others - my mallet still looks close to new, despite knocking in several bats (not for three hours per bat, though - several ten minute sessions, focussing on the edge and toe, followed by nets etc, for me).