Or better yet, know your limitations and avoid getting stuck. But, being a realist, do indeed have a means of self recovery.
One of these days I'll calculate the miles I've spent in 2wd vs 4wd and graph the locations and terrain type in which 4x4 was required. We did 3400 miles thru the Rockies recently and only used 4wd (and low range) to conquer Imogene and Engineer passes. Engineer needed 4x4 because of the thin layer of ice on the last 1000ft and Imogene due to the steepness and loose rocks. Between the two, that was about 40 miles of the trip. We even traveled about 120 miles in Wyoming on muddy roads, in 2wd. I've had plenty of other experiences, but those are fresh in mind. I suppose its safe to say, when you need four wheel drive... you actually NEED it.