But it also seems reasonable that some explorers might just be in a hurry to find the Northwest Passage, and they might save the time and move on, hoping to gain prestige in other ways. Yet other explorers might prioritize looking for remains of the Franklin Expedition, etc.
I think those are the two main strategies in the game: go for the tokens (which costs you a lot of actions) or go for the race to the NW passage.
And a combination of both of course.
@OP: seeing how much it costs you to pick up those tokens it would slow down the game tremendously if everyone had to pick them up.