The study design seems silly. The subjects did better recalling scents after one hour when they had that whole hour to continue smelling any lingering particles of the scent. That's surprising?
While I'm not a scientist in the given field, my personal experience is that people get used to smells very quickly. That's also why historically manual dry rot searchers were notorious for running around buildings fast — once your body gets used to the scent, it's filtered out. I doubt an hour in a given environment would give you much advantage over say five minutes.
It’s actually one of the clearest showcases for humans’ astonishing talent of adapting to their surroundings. You can throw humans in shit-filled holes and, after a few hours, they just won’t care about the smell. It shows, at micro level, the sort of skill that led our species to planet domination.