Odbc voicemail MWI polling

I’m using ODBC for voicemail storage and in trying to track down some some sporadic load issues found Asterisk is running 3 SELECT COUNT (*) statements per monitored mailbox approximately every 30 seconds.

Pollmailboxes in voicemail.conf seems like it would control this behavior. It was commented out, I’ve also tried setting it to no and yes while setting the polling freqency and see no change in the queries. I’m on Asterisk 11.20, it looks like similar code is in 13.4 too. Does anybody know if that’s the expected behavior?