Y'all is efficient. It is just one syllable. Asking the question, "Y'all eat?" Is twice as fast compared to, "Did you all eat?" Of course, I use it because I'm from the south eastern US, not because it's fast.
And to me this just raises the question I often ask myself: whether I'm the only person born in the US in the past fifty years who continues to use the perfect tense and distinguish semantically between it and the simple past. I say "did you eat?" when I want to know whether you ate at a specific, single point in time in the past (and you and I both know which one I mean) -- and you no longer have the opportunity or…
English isn’t a programming language.
All of the questions you’re asked are abstractions of a different question or a series of questions.
Many of them have multiple meanings and you pick the most likely set based on context.