On my original Prusa MK3 (assembled by Prusa) I had a bed variance of 0.6mm across the whole bed. The afterwards integrated 7×7 mesh bed leveling did work but for my work I always found that the bed needs to be as flat as possible in the beginning. Agreed you won’t notice it on smaller parts but when printing bigger functional parts across the whole surface and need the bottom of the parts to be as flat as possible i.e. […]
do it yourself