Is it for SEO okay to mix the subfolder structure between /lang/ & /lang-country/?

Question

We are currently maintaining country folders like

www.example.net/de/
www.example.net/fr/

Now we are thinking about Swiss with 3 languages (it, de, fr). I think it's bad to change all the current directories. Is it okay to only add the region if necessary? For example:

www.example.net/de/ = German speaking, not Swiss
www.example.net/fr/
www.example.net/it/
www.example.net/de-CH/ = German speaking, Swiss only
www.example.net/it-CH/
www.example.net/fr-CH/

So: Is it for SEO okay to mix the subfolder structure between /lang/ & /lang-country/?

Answer 1

This should be fine.

It probably doesn’t affect SEO. Consumers would have no reason to parse the URL path segment if they could just parse the rel-alternate+hreflang markup instead, which is typically easier and more reliable. Any way, even if the URL path segment is used by some consumers, both types are valid language tags after all.

For what it’s worth, Mozilla does this for their Firefox add-on site, too:

• es: https://addons.mozilla.org/es/firefox/addon/noscript/
• de: https://addons.mozilla.org/de/firefox/addon/noscript/
• en-GB: https://addons.mozilla.org/en-GB/firefox/addon/noscript/
• en-US: https://addons.mozilla.org/en-US/firefox/addon/noscript/
• (en and unknown values redirect to en-US)
• (de-DE/de-CH redirect to de)