"Do you think you could learn something like Powershell in 20 hours?"

Depends, for me I would need a task that is to be done with Powershell. Then I would focus on completing that task. When said task is done does that mean I learned Powershell? Maybe not but at least I'd be able to add that to the list of tools I've used and I could say I know Powershell.

Or the ever popular saying, "I know enough to be dangerous"! 🙂