No, soft drinks sold at cinemas in the 60s were much larger than they are today, and no one could hold that much fluid for much more than two hours. The answer

No, soft drinks sold at cinemas in the 60s were much larger than they are today, and no one could hold that much fluid for much more than two hours. The answers you seek are here: https://en.wikipedia.org/wiki/Cue_mark https://en.wikipedia.org/wiki/Cue_mark, specifically https://en.wikipedia.org/wiki/Cue_mark#Use https://en.wikipedia.org/wiki/Cue_mark#Use And the answer to your question, as you now know, is still "no".