Traditional Japanese haiku are structured that way, but that convention is not necessarily followed in English. (Japanese haiku are also written on a single line, while 3 lines are most commonly used in English.) English haiku tend to follow the spirit of the Japanese haiku, but …

Is that sort of like following “the convention of birth control”, but just winging it? 🤪

… the emphasis is on nature, seasonal changes, and strong imagery.

I was corrected myself by a University professor, not an elementary school teacher. Is the person you quote a Japanese person who is a literature expert?