I've read that if you don't wheel often, it's a good idea once a month to lock in your hubs for a few miles, to splash lubrication up on the bearings.
If this is true, why not just leave the hubs locked in all the time? Then you'll get constant lubrication, and if you need to shift into
4wd in snowy/muddy/rainy conditions, you won't have to mess with getting out in the sloppy weather and manually locking the hubs in.