I don't think I've ever run out when out on a long well planned trip.
It's the short, casual, spur of the moment runs that catch you unprepared.
I have run dry on a late night recovery run in our backyard playground, Knik Valley.
I went in expecting to help winch a rig out of a swampy "stuck". Turned out that the guy couldn't remember exactly where the rig was or how to get there. All we had was a GPS fix. Had to spend some time casting around in tight, twisty and mucky ATV trails in an area that had been one disrupted beaver pond laid on top of another for a couple of centuries at least. The ground was a mix of mud and rotting trees and branches. We were within 200-300 yards of the rig forever it seemed, but had to keep backing out and trying again before we found it.
Then it turned out to have a shattered front diff and a busted oil pan. I had to drag it 15 miles back to the trailhead Low range most of the way. No one else had a rig hefty enough to drag the POS Dodge Dakota through the mud, water and soft sand. I had gone in without filling the tank and I had no fuel cans with me. It was just a run into the backyard after all.
At about 3 in the morning we had to siphon fuel from one of the other rigs when I ran out. A jeep.
A few years further back we were once again coming off a trail real late. I didn't run out but the Pig I was driving was real low. We were trying to get up a very slick hill and no one could make it. I was locked at both ends and had chains on but still couldn't claw up the slick clay that had been rained on after we came down it. Everyone else was even worse off. We located another potential route up the hill, but it was so steep that as I positioned to start up the slope the pickup sucked air. One of the other guys had a 5 gallon can so it went in my rig so that I could get to the top and then get the others up. They all charged as far as they could and then the guys standing there with the strap rigged to my rig would throw it on the tow hook as soon as their forward motion stopped.
As we headed down the road from the trail head on the way home (at 5 am) the guy whose can went in my rig... ran out of gas. We siphoned some back from my rig to get to the nearest fuel stop.
These days I never hit any trail without a full tank, and never hit any trail beyond the few that are withing 15 minutes drive of the house with at least a couple of cans too.
I don't usually carry water cans, since in most of the places I go you can drink from the streams and rivers with no concerns
Mark...
onhand for same type of situations... 
after that I started Bringing fuel cans.
Do like I do. Make your 
you can integrate it with a CO2 onboard air system (or vice versa) Then. . whoo hoo
