Under what circumstances it is beneficial to asynchronously read a single file?

Question

I am new to python AIO, trying to learn. I am looking at the aiofiles example:

async with aiofiles.open('filename') as f:
    async for line in f:

and wondering under what circumstances it makes sense to asynchronously read a single file? I understand IO operations will let the CPU do something else, but how this can be turned into a performance benefit?