I was always concerned that the electronic transfer case shifter would fail me in my 89 Ranger. The only time it did not work is once when I forgot to reconnect the connector to the push button switch after doing some work under the dash. I had it for almost 200,000 miles without any problems with the shifter, transfer case or the auto hubs. It saw plenty of tough off-road stuff without extreme abuse.
I think it is a good idea to put it into 4WD low every once in a while just to know if it is working or not. It is more fun to do this if you are off-road and need to put it in 4WD low.
2002 FX4 Bright Red Supercab 4.0 SOHC, manual 5-spd & Tcase, 33" BFG MTs, K&N air filter, Modified air box inlet, Gibson SS cat. back exhaust, Bama flash, Hidden Hitch round receiver, Rear helper air springs, Electric trailer brake controller, Line-X bed liner, WAAG bar with KC lights and Wildernest shell.