After reading the Hardening WordPress article I realise a good permission scheme is essential to the security of my WordPress installation. The article suggests a possible permissions scheme but my question is: considering WordPress arrives 'out-of-the-box' with a default permission scheme in place, do I need change it? If so, please explain why.
As the article suggests, it's only a 'possible' permissions scheme. So there is no quick answer to 'yes' or 'no' in terms of settings the correct permission for files/folders in your particular hosting environment.
My suggestion is to keep it as 'out-of-the-box' unless you run into an issue which requires you to adjust permissions in order for particular feature (media upload) or plugins (caching) to work. You can also contact your hosting provider's support ticket and have them run a security audit for you.