Error response behaviour poor

1) Takes ages to `request_url()` due to retrying. Should probably fail straightaway on 404?

2) Raises an incredibly generic, minimal information error:
`RuntimeError: Max retries exceeded for <url>`
rather than the original error. (Logs do contain more info)

3) It's impossible to do any additional handling - e.g. "If it's a 404, that's fine; skip to the next item"
