I would say what changes for us has a lot more to do with the type of trip ( do I have to carry it all or are we using boat or ATV ? Is it a fly out with weight constraints? Is it early season or later fall? Ocean based or interior?) than the actual length of the trip.
For an apples to apples comparison, for a backpack based hunt of 3 days, vs a backpack based hunt of 12 days, the only thing that changes for us is really the amount of food, fuel and batteries (or solar charger to recharge devices). Otherwise, the clothing, shelter and sleep system and stove etc will be about the same regardless of the length of the trip.
for summer and early fall backpack based trips, I carry layers but the only actual duplicate items are one pair of extra sleep socks (just wear the same other socks everyday, if they get wet or not....always have a dry pair to sleep in) and one spare pair of underwear. On shorter trips I sometimes don't need the extra underwear, but I always bring it along to swap into if the first pair gets wet or grungy.
I carry Coleman soap sheets in our possibles kit regardless of trip duration, and use these for hand, body or laundry soap in the event I want to wash something or myself in the creek. Low weight penalty, so they are always in our gear...
There will always be exceptions based on the logistics involved. For fly out trips where we might get stranded for bad weather, especially in the later season we tend to bring more duplicates. We usually have at least one extra shelter along for Oct goat or deer hunts in Kodiak for example, which allows us to spike out from a base camp but can also serve as an emergency shelter in the event of a storm or catastrophic tent failure. I might also bring along another pair of extra socks for a trip like that, as well as maybe a pair of fleece pants or change of base layers...they can stay at base camp but offer added insurance if the weather is bad and we get stranded or I fall in the creek (I need spare clothes if I get wet more likely in October than in July, odds are...)