How strict is the date format requirements in GEDCOM files?

On Ancestry I enter full dates (like 3 June 2026) but GEDCOM always lists the months in abbreviated form. I don't like using the abbreviations because it's so easy to make mistakes. Jan, Jun and Jul are only one letter apart between each, so it's easier to screw up as compared to typing January, June and July.

It took a long time to get used to the d/m/y format as compared to m/d/y since I'm from the US. Does listing a full month really screw up the code of a GEDCOM file? And since the variations are limited and very obvious, if it is an issue, why?