...after Opening Day.

I know this answer depends somewhat on where you hunt and how much hunting pressure there is. I am also referring to M/L/rifle/shotgun only, not bow

Where I hunt in New England (Maine/NH) it seems the deer have gotten the message after the 2nd day of the hunting season. After Opening Day and the following day, the deer seem to be much more on alert when I see them from my treestand. I would also say there is moderate to lighthunting pressure where I hunt. Of course the deer sighting seem to decrease and the hunting days increase.

Have you found this to be true in your area?