I interviewed for a company in May that gave me a takehome that was very vague and probably would have taken my entire weekend to do it. So I declined and moved on.
My rule of thumb though is to spend no more than 2-3 hours on a takehome challenge. If you think it will take any longer, don't do it. And lack of any feedback from the company pass or fail is ridiculous to me.
As for your submission it LGTM. I'd bring you in and probably ask about how you'd want to improve it if you had more time, expecting the usual best practices and scalability things. I'm not sure your Python experience, but given the context of the problem space, I'd ask why you wouldn't consider other approaches like adding the url metric logic in a decorator or some other modularization that could be reused to "performance test" future API calls. I'd ask about your submission's lack of tests (getting at unit tests here) and how you could refactor your solution to facilitate better test coverage if you had more time. Deepdive about the tradeoffs of using Python coroutines as opposed to other concurrency methods.
Unfortunately there's always going to be a desperate developer out there who will spend every waking second overengineering a solution that will set a high standard for everyone else to be compared against.
Wishing you the best of luck!