Deer are partially nocturnal animals. Each time you sit by a stand walk through an area, you leave scent behind. If your scent is around all the time, the deer will be aware of your presence and avoid the area during daylight hours.
I disagree, the deer at my camp are creatures of habit. It doesn't matter how much sent I leave in my woods the deer are always there, they seem to have gotten used to human scent in the woods and it doesn't bother them. During gun season we shot 2 bucks out of the same stand 1 week apart. The second dropped 5 feet from the first's gut pile. If human scent played such a big role I don't think you would have seen any deer in that area for a while. I think alot of this scent business is brought on by these big companys to get you to buy there products. Its all a scam.