A few levels you have to go through in my experience:
Can you understand a local?
Can you be understood by a local?
Can you do both of the above consistently?
Can you understand locals talking amongst themselves (consistently)?
From that point onwards, it's diminishing returns. Though it doesn't hurt to refine your skill as you go.
Can you understand a local?
Can you be understood by a local?
Can you do both of the above consistently?
Can you understand locals talking amongst themselves (consistently)?
From that point onwards, it's diminishing returns. Though it doesn't hurt to refine your skill as you go.