YOU SAID:

i spend my time productively once in a blue moon

INTO JAPANESE

私はブルームーンに一度だけ生産的に時間を過ごします

BACK INTO ENGLISH

I only spend time productively once in a blue moon

INTO JAPANESE

生産的に時間を過ごすのはブルームーンに一度だけ

BACK INTO ENGLISH

You only get to spend your time productively once in a blue moon.

INTO JAPANESE

生産的に時間を過ごせるのは、ブルームーンに一度だけです。

BACK INTO ENGLISH

You only get to spend your time productively once in a blue moon.