Engagement peaking once a month can happen when content is posted at certain times when people are more active, such as salary periods, weekends, or special events. It can also happen when one post performs very well and brings more people who interact with other posts for a short time. After that, engagement drops again until another strong post appears. This shows that content quality and posting time both matter. Checking which post caused the spike can help repeat the result. What usually causes monthly engagement spikes?