Carrying the same gear for an alaskan midwinter and a sarahan midsummer would be simply a death sentence.
The other half, that I didn't mention, was more temperate environments. :P For desert, of course he'd have more water, and always appropriate clothing.
But honestly, he's taken a knife, clothing, and one or two widgets with him into most of his forays. With, say, something like a modified PSP w/ a Heatsheet and a few FAK items, say in a hard drive case or a pocket in a water bottle carrier, his clothing, and a knife, he'd be in better shape. Think of it this way- you drop your pack or your snowmobile to grab a photo or make a cat hole, and you go back to were you think you left your pack, and you know you didn't cross the trail, and.... ah, man....
That has always been his premise. This way, he'd be more prepared.