They won’t. I tested them over 5 years after that.
If you want to believe me. It works. :
Something is the partition geometry and surface is corrected/altered. I’ve spent 5 hours helping a guy in the US (He was here at avast forums too) by IM and it worked.
I’ve tested in quite some old HDD too. The bad blocks do not come back.
This does not work sometimes and then, for any reason, the bad blocks reproduce themselves like rabbits and whole disk, files, etc. are lost.
This is not a solution but a final word about the issue.