I'm assuming the child is question is not so much adversarial so much as ADHD. They'll be actively looking to divert their attention to more stimulating activities than playing an instrument but not attempting to cheat the system. And I'm assuming a parent is present but not necessarily in full control of the child. Or it could work equally well for an adult in a similar situation.

For the non-adversary who wants something similar in nature, that might help them practice, why not? Not everyone is trying to cheat.