Interesting. I hike a fair amount. I'd say 18 is a pretty good number of miles. It's somewhat terrain dependent (are you in flat country or the middle of the Rockies?), but still even at 3mph which is a pretty good walking speed for most folks, that's a minium of 6 hours walking not including any water breaks and the like. In hilly or difficult terrain, 2mph is more realistic, which would entail 9 hours of walking. Given that the event happened at about noon (in this case), 6 to 9 hours of walking this time of year may not be the way to go.

True, XC travel doesn't necessarily cut your travel time. One has to make an assessment. Sometimes XC travel is a worthwhile savings; sometimes it's a fool's errand. STOP (Stop, Think, Observe, Plan) is a good one to keep in mind. You're absolutely right that the risk level generally goes up on XC travel and that it may not save you any time. One has to ask: "Is it worth it?"