Suppose a student neglects the period available for preparing for an important examination, then complains after the results that there was insufficient time. Applying “bi-l-ṣayfi ḍayyaʿti al-laban” does not claim that the student wasted actual milk in a particular season.
Original pattern: failing to preserve a benefit when the chance existed.
New pattern: neglecting preparation and wishing for its benefits after the opportunity passes.
Resemblance: allowing a time-sensitive opportunity to disappear and then regretting its loss.
This illustrates transfer of a complete pattern without rewriting the proverb's words to mention students, examinations, or preparation.