You're right Dave, it's pretty tempting and sometimes a tough decision to make, but it's kinda cool that a lot of the challenges kind of connect with each other in such a way that if you fail at getting the best score at one of them they can be abandoned for another. For example: bottom girder challenge->1-1 highscore -> 4 man challenge or normal game (or any of the 'highscore by level 'x' challenges').
And the other reason being how pretigious one run is over the other. Given 1-1 is still pretty up there to me I'd abandon another good run to try and get 14K on 1-1.
If I had to rank DK scores/challenges to how pretigeous. I'd probably have the list like this:
-DK total points (Hammer Allowed) : Of course this would have to be first
-DK total points (No Hammer)
-Best 1-1 (Yes, I still think 1-1 challenge is above the best lev 5 start)
-Best Level 5 start
-Best score by 2-3
-<everything else> (All of the other challenges of too unique to really put a value on it yet.