The books don't explain any of this recent globetrotting, because it isn't in the books. Again, you can say we're only seeing snippets of storylines, but the storylines intersect. So unless the Night King is marching on a treadmill, they should already be in Kings Landing or Dorne by the time Jon skips from Winterfell to Dragonstone, then all the damn way back to Eastwatch for this latest dumb quest.
It's a fantasy series, but even fantasy series should obey the rules of the world they create, and one of the rules is that travel is as slow as it was in the real Middle Ages (unless you've got a dragon to ride). When they repeatedly trash those rules, it just starts to look more and more contrived.