yeah ive revegged once years ago.
I had a plant that was well into 12/12 and knocked off a limb of the plant. i freaked out at the time cause i didnt know what to do then stuffed it into a rockwool cube and tried to clone it in veg.it took forever and grew into a weird looking bush. the leaf went weird and the plant structure changed once it became large eough i put it back into flower but it didnt really put out anything of quality.
it takes forever to go back to a regular plant once you reveg. its called a monster-cropping and i wouldnt do it again on purpose
it really depends on how far along into 12/12 you are but it will definitely freak out a plant