Measuring timing, frequency, and relevance of sends helps reveal whether messages arrive at the right moment or feel intrusive. High click or engagement rates suggest value, while quick dismissals or muted notifications signal growing annoyance. Repeated ignoring, uninstalling apps, or turning off alerts shows the line has already been crossed. Notification flow logs act like heatmaps, showing where users drop off or start refining preferences. These patterns help teams adjust cadence, personalize content, and pick better delivery times for relevance.