Volume triggers on Event Log errors

Hi, apologies in advance if this is answered elsewhere but I couldn't find anything.

My volume trigger notification for specific event log errors aren't working as I'd expect. I'm supposed to get a notification if I get >3 occurrences (new records) per hour. However, notifications are being triggered on a single occurrence. The first time it happened the log showed there were 10,225,869 new records and on the second occasion it was 20,354,331 so I can see why PRTG sent the notification but I don't understand how it arrived at the record count. Can anyone explain this to me please?