AMWTSSDs, SD cards and USB sticks move data around inside to spread wear. They keep a few spare blocks for this, and a computer can't address them directly.
Secure Erase overwrites every block the drive lets a computer see, and can read them all back to check. That is what recovery apps read, so after an erase they find nothing, including AMWT Desktop's own Data Recovery.
A copy of old data can in theory survive in a spare block, and reading it takes laboratory equipment that opens the drive. If the drive held something that must never be read, such as medical or legal records, erase it and then destroy it physically.
Several passes don't reach the spare blocks either; they only take longer. One pass of zeros is the right choice for these drives.
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