Confluence cluster safety job fires in odd intervals

The ClusterSafetyJob is a task that safeguards against data integrity issues by preventing multiple Confluence servers (or Confluence nodes outside of a recognized cluster) from updating the same database.

Expected behavior is that it runs every 30 seconds, but it is actually oddly running at 00 and 15 seconds of every minute (instead of the expected 00 and 30). This is observed through Confluence Admin > Scheduled Jobs, for example:

18:18:15
18:18:00
18:17:15
18:17:00

That said, this is very unlikely to have impact on DB integrity, given that the job still runs very frequently, hence the minor priority designation.