I hunt in a private club in the Chicago suburbs that has been hunting out of the exact same blinds for decades. We have a lot of resident ducks. First couple days very good shooting and then it really slows until new ducks show up, usually somewhere around the 3rd week and then things pick up and it cycles up and down as new birds come through. However, when things stabilize, the birds very quickly learn where the safe ponds are. I will go hunting in the morning before work and see nothing, but drive home to get ready for work and there will be a pile of ducks and/or geese on the pond across the street from my house and ducks on every pond on the way to work.
By the time they got to you, they have probably been through this routine a few times. I think you are still going to see educated birds, whether or not you leave them alone for a couple seasons or not.
Improved habit will definitely help draw them in and fatten them up for the flight back north. Being very careful to only shoot small groups would probably help to. Dead ducks don't learn anything