Zibgee Battery Life when HA is shut down

If I leave my house for an extended period of time (say 1 month), I sometimes shut everything down (i.e. turn off the power).

I realize this may vary from device to device, but is there a general rule with respect to what battery powered Zigbee devices do - i.e. do they continue to try to join the (now non existent Zigbee) network of do they effectively hibernate.

The main reason for the question is, is it worth it, to go round all the devices pulling out the batteries?

If battery life is about the same (or just a bit worse) I can live with replacing the batteries more or less on a normal schedule, but if the devices are going to eat the batteries during that time, I will make the effort to remove all the batteries.

They (end devices) try to talk to thier parent device. If the parent is the coordinator and the coordinator is down they panic and try to reparent (approx 25 min no parent, this is why you can force devices to start resetting links by turning off parents.) then they find a valid parent they stop looking. If they don't it'll loop like this three-four times. Then depending on the device try a broader rejoin or quit trying.

Depends on the device what it does from there. Most I've seen quit. Some just keep going.

Either way have more than one powered parent available that isn't the coordinator you'll probably be fine. They reparent to a valid repeating parent, done. If on the other habd you have a sparse network...

You're the only one who can tell that.