Rarely use my cruise because it INCREASES fuel consumption for me.
Darn thing wants to keep the same speed UP hills and slows the truck down, down hill. That increases fuel mileage. That's especially true while towing.
I use an "educated foot" to slow on hills and speed up going down. Fuel mileage is improved if you do that.
As for a truck "learning" your habits, there is something like that with the transmission. I think it's bull#*!. Also think the dealer is giving you a version of the same. My take on your relatively poor fuel mileage has multiple issues.
I think there might be something wrong with your particular truck. I also think there might be something wrong with your driving habits. That could be hard acceleration, hard stops, lack of coasting, abrupt throttle pressure, pushing the rpm's up when cold, more city driving that you say, hard cornering, and/or a variation of all those things based on your past driving experiences.
Watch that silly fuel consumption bar for a while and play with your throttle foot to find how you can get it to show up to or over 30mpg as much as possible.
Don't wreck doing it either. Sure it will be a PIA looking down at that thing after a while. It will be less of a pain in the wallet if you find something about your driving habits that can help you improve the fuel mileage.