I think the main thing is that they need to stop in order to get their bearings and actually navigate. The map they have is big and unwieldy (made worse by the fact that they keep unfolding it to read rather than just looking at the quadrant they're actually in) compared to the ones you typically see in orienteering competitions, and they also don't have the stamina and navigational skills to do it while on the move.
I think that most of the conversations in this chapter happens as they are walking, though..