In Chinese culture, maintaining social harmony and protecting one's own and others' “face” (面子, miànzi) is important. 说错了 (shuō cuò le) plays a subtle but key role in this. By using it, you immediately frame a mistake as a simple “slip of the tongue” (口误, kǒu wù) rather than a sign of ignorance or incompetence. It's a quick, efficient way to fix a factual error without a major loss of face. This contrasts with the Western tendency to sometimes over-apologize for minor errors. Saying “Oh my god, I'm so sorry, I meant Tuesday!” might sound overly dramatic in a Chinese context where a simple “啊,说错了,是星期二” (Ā, shuō cuò le, shì xīngqī'èr) - “Ah, I said it wrong, it's Tuesday” - is perfectly sufficient. 说错了 (shuō cuò le) is functional and transactional; it corrects the record and allows the conversation to move on smoothly, preserving harmony.
This phrase is extremely common in all informal and semi-formal situations.