They were a few threads on here back in time about which were printed first and a boardie who worked in the printers said that the UK copies were always printed first as they were used as test lots to prove everything was working correctly, not many people here understandably were keen to hear this and lots of arguing ensued
I would bet blades were changed/sharpened as and when required and not before, if it was a big deal, the copies with chipping would have failed quality control and never made it out, I dont think they cared enough, they were only comics