That’s not right:
- you - singular
- y’all - plural
- all y’all - superplural
Y’all refers to multiple people, all y’all refers to multiple groups of people
I feel like y’all covers up to ~3 and “all y’all” (my favourite Americanism) is reserved for more than that?
As a born and raised southerner, y’all can be used for one person or many, with no clear limit on the number. All y’all is used to stress a point or to make it clear that it references everyone capable of hearing the message or just anyone who could be intended. All y’all is mainly used, in real world applications, in the sentence “all y’all can go fuck y’allself” or similar.