User753101303 posted
Hi,
If your site runs both using "en-us", "en-gb" it allows to handle common translations in the neutral resource file and to use "en-us" or "en-gb" only when there is a difference (such as for "color" vs "colour"). And so if you later change a common translation
you'll have to update a single file rather than having to do the same change twice.
Not really, if your site is available using "en-us", "de-de" and "fr-fr" you'll have a single resource file for each language and using a neutral culture or a specific culture resource file won't make any real difference.