I have a 2012 4 runner SR5 with part time 4wd. Toyota recommends that the 4H be engaged for at least 10 miles/month in order to keep the gears lubricated.
Why is the JK different?
it probably has an electronic actuator that shifts ranges. I once took a 4x4 explorer to the top of Pikes Peak. the top half of the trip is gravel. when we got back down to the asphalt it would not come out of 4WD. 4wd hadnt been used for years.
My brother (mechanical engineer and heck of a good mechanic) recommended that I "exercise" the 4WD from time to time. Reason: splashes fresh, warm lube on all of the seals, fully soaks all of the moving parts, prevents sludge buildup, and "flexes" all of the linkages. It also helps to insure that the system works as designed when you really do need it and reach for the selector lever, yank on it, and nothing happens. I just pop mine into 4H on dirt and gravel roads every weekend when I am headed out fishing.
When I bought my 2012, it took 1.5 years for me to engage 4wd. It still goes into high and low like butter.