Turkey is only good for a few days in the fridge after cooking, plus I love cold turkey sandwiches but I could probably make at least 20 from a full turkey. I wouldn’t eat that many in the 3 days before the turkey starts going bad.
Turkey freezes pretty well, so if you are incline to roast a whole turkey (or a turkey breast), just portion it in sandwich sized amounts and freeze.
I get the same cravings as the OP, and no deli makes turkey good enough to satisfy them.
I like to buy a half-breast of turkey and roast it myself; it only takes about 40 minutes tops. One half-breast is good for about four generous sandwiches.
Ok, last night I ambled by the deli counter at Kroger, and indeed saw a couple of shrink wrapped turkey breasts in the case which looked like they had been cut straight from the bird. So I will be buying some next time to see if I need to change my mind 
Panera Bread. Had a turkey sandwich there yesterday, and was a little annoyed that the turkey was in irregular chunks instead of neat, even slices. They kept falling out of the sandwich.
Also, Boston Market. They cut their turkey into more even slices, but they’re much thicker than cold cuts, and are sliced right from the bird.