If you have all of that, then you, like me, are in "4WD" all the time. We have the option of locking the center diff for better traction, and/or using 4LO for nasty situations where we'd otherwise (and still may) be stuck.
This is my 5th 4WD over the last 25 years, and I've only ever had to use 4LO twice - you'll likely never have to use it unless you are hard-core into off-roading. This is, however, my first quasi-AWD so I do not know how often or not I will need to mess with the center diff lock feature. Call me after it snows here...lol