Perhaps a rename to `REQUEST_TIMEOUT_DEFAULT` to highlight this is a fallback value? I do prefer defaults to be more higher up though, so it could also be an idea to not make `new_client` accept an `Option` and specify this default somewhere in `main`.

I personally prefer keeping the parsing with clap. Like this: ```suggestion #[clap(long = "timeout", global = true, value_parser = |t: &str| -> Result<Duration> { Ok(t.parse().map(Duration::from_secs)?) })] ``` But then a `fn` instead of inlined.