Sounds like the cook aide outgrew their job almost immediately. So, I would suggest as an answer to outgrow one's job, and obvious variants required by the context.

If you Google outgrow a job, you'll get tons of hits -- and advice on what to do about it.

Sounds like the cook aide outgrew their job almost immediately, i.e., hit a learning/personal development ceiling. So, I would suggest as an answer the idiom to outgrow one's job, and obvious variants required by the context.

If you Google outgrow a job, you'll get tons of hits -- and advice on how to tell you've outgrown your job and what to do about it.