The highest-signal metrics are voluntary attendance rate (whether employees choose the office rather than comply with it) and acoustic focus space utilisation (whether employees use enclosed acoustic spaces for their most demanding work). Both are leading indicators of the engagement and retention outcomes that ultimately matter. Trailing indicators — turnover rate, engagement index trends — confirm whether the policy is working but arrive too late to enable rapid course correction. HR should have both leading and trailing metrics in their hybrid working dashboard, reviewed monthly.