Final answer:
The purpose of rechecking weather conditions at regular intervals is to minimize the chances of missing significant weather changes and determine the need for a SPECI observation.
Step-by-step explanation:
The purpose of rechecking weather conditions at intervals not to exceed 20 minutes is to minimize the chances of missing any significant weather changes.
Weather technicians may not detect and report all weather changes as they occur, so rechecking the conditions helps ensure accurate and up-to-date weather reports. Additionally, the rechecks are done to determine the need for a SPECI observation, which is a special weather observation made to report changes in weather conditions that pose a significant hazard to aviation.