Me again!!

OK, imagine writing a scene where your characters are making their way through a forest or desert or whatever, and you want to give the impression that the journey is a long one, but you don't want to waste time and space prattling on about it. Would you write something like this:
EXAMPLE: (Taken from THE MUMMY)
DO SEVERAL TIME DISSOLVES: showing the majesty of the
desert, and our heroes getting deeper and deeper into it.
Thanks!!!
Basically, for contemporary spec scripts scripts (and even the original -- and by original, I'm talking about the original remake -- Mummy is a few years old now) are really looking to cut to the chase in terms of this kind of stuff -- exposition, set-up, establishing characters.
You should be looking to do this with the minimum of fuss and bother.
Unless something of significance is happening along the way, there's really no reason to show people "along the way."
If they start in New York City and you cut to them climbing K-2, the audience will understand that they've gone a long way, that they've been on planes, trains, automobiles, that they've changed their money, had their passports stamped, changes their clothes several times. You don't need a bunch of dissolves showing them doing any of this -- unless some aspect of it has *story* significance -- unless you're showing it to us to set us up for that's going to happen later.
You refer to that scene where they change clothes in National Treasure -- yes, they change their clothes in that scene, but that's not what that scene is about (if I'm recalling correctly) -- this is a scene where they're figuring out the next clue and having some character interchange -- and by the way, changing their clothes. The clothes-changing is simply giving them some business and giving them a place for the scene to happen and only incidentally getting them out of those clothes (which could easily have been done at a number of earlier places).
NMS