Why it works
Morale drifts slowly and then all at once — by the time it shows up in a 1:1, someone's already updating their CV. A standing monthly prompt gives everyone a low-friction channel to flag how things actually feel, and the trend across months tells you more than any single answer. The three questions are timeless, so one recurring email becomes an ongoing pulse you never have to rebuild.
Make it yours
Offer the "reply just to me" option so people can be honest. Keep the questions identical month to month — the value is in comparing this month's answers to the last, and changing the questions resets that signal.