[elevensies]

It depends what your goal is. If you're trying to get a specific person to say a certain thing, then it works well. If I wanted you to confess to a conspiracy with my political enemies so I could execute them, the fingernail removal strategy works fine.

If you're trying to figure out the truth in a fluid and confusing environment, then it doesn't work well because it motivates the victim to do whatever they can do to end the conversation as quickly as possible.