Usually the full time 4wd function (center "diff" open) is enough for most winter driving.
The only time I find that it lets me down is when things are super slick with slushy stuff, hard packed snow, or ice. With that, the truck tends to get a bit unpredictable as the power shifts back and forth between the front and the rear of the vehicle with the losses of traction (not sure if the traction control on yours would minimize this). It is like driving front wheel drive one minute and then rear wheel drive the next, but you have no idea at any given moment which you are driving. That's when I start switching to part time 4wd (center "diff" locked) to eliminate that variable.
If you are getting some traction front and back, this isn't really a concern. Just feel it out as you go.