I think it depends on which Nationals you're talking about.
If the focus is indoors, you only get so many shots to run on fast tracks - like last weekend at the Armory, BU and Penn St - and you have to take those chances. It's going to be hard to chase times at Dartmouth at the end of the month.
Columbia's guys seem to be starting off more slowly than previous years, but they also get to run the next two weekends at the Armory, so I suspect we'll see them moving into the lists after those meets.
If an athlete has a real chance for NCAA outdoors, running a bunch in January makes for a very long season.