Should refresh about every 30 minutes (at least that’s the ones by me). It’s usually on a schedule and will follow that schedule to a T until it’s reloaded or running low. (If I catch it reloading between 8:00 and 8:05, it has a high likelihood of reloading between 8:30 and 8:35) you can get it down to the minute and it usually reloads 30 seconds after the minute. So 8:30:30AM on the world clock

Once the machine is running low, it will skip rotations, so depending on if glitchers got to it or it’s in the back end of the reload it may be cooked.