On some filesystems the data is still there but the filenames associated with it are gone or mangled. That makes it harder to recover things. In addition, while it’s true that the contents are only overwritten when you write data to the disk, data is constantly being written to the disk. Caches are being updated, backup files are being saved, updates are being downloaded, etc. If you only delete one file the odds are decent that that part of the disk might not be used next. But, if you nuke the entire drive, then you’re probably going to lose something.
On the upside, they specified D: drive which is typically a lesser used bulk storage drive, so less activity to potentially overwrite the files marked as deleted
On some filesystems the data is still there but the filenames associated with it are gone or mangled. That makes it harder to recover things. In addition, while it’s true that the contents are only overwritten when you write data to the disk, data is constantly being written to the disk. Caches are being updated, backup files are being saved, updates are being downloaded, etc. If you only delete one file the odds are decent that that part of the disk might not be used next. But, if you nuke the entire drive, then you’re probably going to lose something.
On the upside, they specified D: drive which is typically a lesser used bulk storage drive, so less activity to potentially overwrite the files marked as deleted