Imagine stubbing your toe with nails like that. The entire toe nail will be ripped clean off.

Could also be useful for doing research with ebooks. Maybe show a list of bookmarks or the table of contents on one screen and the text on the other screen. Or you could compare different texts easier, showing one on one screen and one on the other. Or use one screen for notes. But I guess people that need to actually do productive research will use a desktop anyways.

A single junior analyst causing such a breach of redacted information would still point towards incompetence on an organisational level. This should really be something every person who works in publishing documents with redacted informations should be trained to spot.