The quest cleanup happens every 1 hour 5 mins, so pretty much randomly spread.
This needs some verification that it does not trip over a new quest activity (which it should not since it is checking expiry date)
This needs to have bulk activities spread like quest reset now does (and therefore might be harder to avoid collisions unless scheduled for :59:59 and takes into account the expiry that is about to happen)
The quest cleanup happens every 1 hour 5 mins, so pretty much randomly spread.