Could I drive around all summer long with a set a manually locking hubs engaged without any major bad effect? Were they designed to be disengaged immediately after use? I suppose the vacuum actuated hubs are the same. as soon as you take it out of 4WD the hubs disengage

I have a Jeep cherokee and they never had any of this. Are my hubs designed different or is the locking feature just a 'bonus' item to prevent wear and as somebody mentioned if you snap an axle off road you can disengage

So I guess my question is can they be left engaged for months at a time or do you have to disengage them immediately after use?

 

or can I leave a set of locking hubs engaged all winter long without anything bad happening?

 

If you leave manual hubs locked in but with transfer case engaged in 2Hi (assuming you can select 2Hi) the only adverse effect would be your entire front driveline spinning and being driven by your front tires contacting the road. More wear and less MPG.
Also, you can leave the hubs locked in in the winter, but only shift into 4Hi when you encounter snow or ice.
Up here in the frozen north, I lock my hubs in about October when the termination dust appears, so I can shift between 2Hi and 4Hi when I drive between backroads and highway. I will unlock the hubs in April unless I know I'm going off-road, then will lock them in but drive in 2Hi until I see soft pavement that I will need 4x4 for.
If you drive in 4Hi with hubs locked in, you will eventually break a u-joint or worse when traction is found in a turn.