Sarumo kikara ochiru
Even monkeys fall off trees
Everyone has his or her bad days
Theres a monkey and you know, monkeys are supposed to be really good at going from tree to tree. So this monkey is basically jumping from tree to tree and he falls off. Well, monkeys arent supposed to fall off trees because theyre tree masters. But it just shows that everyone has their bad days, even if youre supposed to never make mistakes.
Informant read this in a book full of proverbs in Japanese when he was young. Hes heard it used many places many times, mostly in academic settings or work-related situations. The informant first heard it in elementary school. He usually tests well consistently but when he performs below his usual standard, his teacher would often tell him Sarumo kikara ochiru. This made him feel ok about making mistakes and that its fine to have a bad day once in awhile.
I find this proverb very concise because its imagery is so fitting to its meaning. Its also a proverb that everyone can relate to. I bet theres also an English proverb relaying the same message that I cant seem to recall at the moment, but I am almost positive that its out there, exemplifying different versions and varieties of folklore.