Not been really neccesary on modern drives for quite some time. Modern drives do automatic sector re-allocation of bad sectors on the fly. You'll only see actual bad sectors from the filesystem/operating system level (chkdsk/scandisk level) when the drive run out of spare sectors, by which time I wouldn't trust any data to it anymore anyway. The number of actual remappings done can be monitored with a S.M.A.R.T. monitoring tool.