of hundreds of drives (cloud), SSD, Smart Phones, etc. This includes those that have been purposely or accidentally erased and/or physically damaged.
If a disk has all zeros written to it, as far as I know from what I've read there is no hope of recovering the data. There were rumors that the government could do it based on really fine detection of magnetic levels or something -- but it was rumor. There are bounties out there if anyone can pull it off.
I understand data can be recovered when the file entry is removed from an allocation table but data has not been zereod/randomly written over.
tl;dr: single pass is fine -- no need to triple pass erase.
